The story of Fallout 4 takes place in 2302, 25 years after the end of Fallout 3. Starting in New York, specifically in prison, the story takes the character through dozens of locations and what begins as a simple chase turns into a full-scale war.
Part 1 - The Chase
- Gameplay starts with the player creating their character and awakening in Rikers Island, learning that they are an "unofficial" prisoner being held here personally by the Prison Warden. The player and their cell mate, Jessie, are able to create an armed prison riot, overwhelming the guards and getting to the main armory. While there, the player regains their equipment from before the game's start, which includes thousands of bottle caps, but is interrupted by the Prison Warden who kills Jessie and shoots the player.
- Falling to the ground and barely staying conscious, the player watches as the Prison Warden steals their caps, commenting how she was going to be paid much more for handing them over but must leave in a hurry now. After her exit, the player is saved by two other prisoners, Reese and Krieg, who pick the player up and carry them away. This rescue isn't totally out of generosity, however; with New York on lockdown and the player being the only prisoner the faction does not know about, Reese and Krieg need the player's help to escape the city.
- The player performs a small number of quests, including surveillance in Wall Market and stealing prison documents, the player will soon learn that the Prison Warden has fled the city, heading for the Commonwealth. The player should decide at this point to chase down the Warden, whether it be for answers, vengeance, or to get their damn bottle caps back. The end result is the player and company stealing their very own vehicle, the Chryslus Fortress, and escaping the city. If the player is found during this escape, the city as a whole will turn hostile, making things difficult later on.
- The player heads for the Commonwealth with Reese becoming a full-fledged companion now, wishing to actually help the player, and Krieg acting as a driver, wanting just to kill the Warden for personal reasons. At the Commonwealth, the player finds that the region's most famous faction, the Institute, is in the middle of a civil war, while fighting another war with the region's second biggest faction, the Union. The player can choose to engage in this conflict now, but it isn't required to later on.
- The player follows multiple clues to find where the Warden is, including finding her temporary home in the small settlement of Wonderland, until learning the Warden has left the Commonwealth and is heading for Ronto. They can also, optionally, find out that it was Ronto that hired the Prison Warden to capture the player. This presents a new problem as reaching the military city of Ronto is normally impossible. Luckily, Krieg has "friends in low places" and knows a smuggler that works out of Ronto. Meeting with him, the player is able to barter to sneak into the city's Lakefront district, but the trip requires temporarily leaving all of your companions behind.
- Despite Ronto being a once peaceful city, the player gets the newly common site of a pair of men being killed by the city's guards. The player must be careful in Ronto, as some guards are willing to shoot the player just for looking at them funny. While going through the city, the player finally catches the Prison Warden in the Lakefront district and a foot chase begins. Upon catching her, the player fights her unarmed, but doesn't have to worry about having a low Unarmed skill as six armed Ronto guards appear and attack both of you with stun weapons.
- The Prison Warden attempts to resist as the guards drag the both of you to their headquarters, Casa Loma, where the leader of Ronto, Logan, is giving a speech to his soldiers revealing their plan to launch an attack on the Commonwealth and the rest of the United States. Logan then departs into a tunnel system underneath the castle and the guards decide to bring the player and the Warden down there to meet him. The tunnels, being more of a cavern, lead to none other than Vault 122, a Vault built underneath Lake Ontario and that Ronto has just recently been able to penetrate its Vault door, gaining access to the technology inside.
- The characters are brought to Logan where he is already speaking with a third prisoner, Gerard the leader of Ronto's resistance group. Instead of being kept within the Vault itself, Logan feels it better to keep you in the small cave system in the exterior (similar to the cave system of Vaults 19 or 22) where he explains his reasoning for wanting the player captured. Turning to the Prison Warden, the Warden begins begging for her life, trying to convince him that "this was part of the plan" and that she handed the player over to Logan "as promised" but he answers by shooting her in the head and referring to her as a "waste of time".
- Explaining the background of Vault 122 a bit, Logan reveals his interest in the Vault. As part of its experiment, the Vault was equipped with very advanced electromagnetic pulse weapons. With various factions, like the Institute and Brotherhood of Steel, having a heavy dependence on technology, they will be rendered powerless thanks to the Vault's weapon. Leaving both the player and Gerard in the cave for "safe keeping", the player can choose to speak with Gerard at any time, at which point he gives one piece of advice: "Make sure to hold your breath".
- As explosions suddenly occur, the ceiling of the caves is destroyed, rushing water from Lake Ontario in to the player's temporary prison. While the Vault is unaffected thanks to its external doors, various men in scuba gear appear and grab the player, Gerard and one of the Ronto guards, taking them into the lake where a small submarine is waiting. Upon entering, Gerard welcomes the player to the resistance and it's revealed the guard is (or at least was) a double agent within Ronto who helped the submarine locate them. The submarine heads for Kingston, the resistance's base, as Gerard reminds the player how Ronto used to be a peaceful faction before Logan's coup. At Kingston, Gerard asks for the player's help, specifically by warning the Commonwealth of the incoming attack and helping them prepare for it. The resistance will attempt to delay Ronto, but there's only so much they can do...
Part 2 - War
The player has approximately two in-game months to prepare the Commonwealth for Ronto's attack. This is an actual time limit, similar to the time limits of the first Fallout, and if the player is not ready by then they will either need to fight Ronto unprepared or fail the main story. Unlike Fallout, failing the main story does not end the game, but the Commonwealth is destroyed and inaccessible and the wasteland become a bit more hostile.
How can we fight them if they can render our androids powerless! Should we just throw sticks and stones at them?”— Marcus
The news of an incoming invasion causes just a little panic, unless you decide to tell the small towns of Quincy or Wonderland, then it's quite a bit of panic. The main two conflicts in the Commonwealth are the civil war in the Institute and the Institute's small war with the Union. The Union is surprisingly easy to convince to stop when they hear of Ronto's plans. Sadly, things are not so easy with the Institute's internal problems. With no current leader within the faction, for this civil war to end they need either Killian or Marcus to step up as the new Dean. While this does not technically require blood shed, there may be a bit of violence as the player picks which leader to back. Afterwards, the new leader will suggest the player go to other regions nearby to recruit possible allies to fight off Ronto, marking the Capital Wasteland and Detroit on the player's map.
He used to be different. Years ago, you would never have imagined him turning into the man he is now. But when he lost Claire... He was never the same.”— Jenny
- The player needs to find a way to stop Ronto's EMP weapons. What better place to look than the people that grew up in Vault 122? Wilson is a small settlement compared to New York or the Commonwealth but it is equally important. The town is filled with former Vault dwellers who are not quite used to live in the wasteland yet. They also know quite a bit of Logan's plans and are willing to help. Jenny, the current leader, comes up with an idea of how to counter the EMP devices when asked. Despite the centuries of electromagnetic pulses going through the Vault and the constantly failing equipment, the Vault's main ZAX computer was never affected by the pulses. Finding out why would require re-entering Vault 122, however, which may seem impossible since that's under Ronto's control... Until Jenny informs you that Vault 122 has two entrances, one of which is just outside of this town.
- Jenny gives the player the codes to access the Vault door and leads the player to the long cave system that leads to the Vault. The cave is safe from critters but is still somewhat creepy. When the Vault door is opened, the player will immediately hear the voices of Ronto soldiers alerted by the door. The player must either engage them in combat or quickly hide before they arrive. While remaining hidden in the Vault is difficult, it is possible with a little skill. When the player reaches the ZAX, it will answer all of the player's questions, including the facts that the other intruders have already removed all of the EMP technology and that the ZAX stays immune to their effects thanks to a special alloy shielding its circuits. Upon request, it will give the player a holotape of the pre-War method of crafting the alloy.
- If this holotape is taken to the Institute in the Commonwealth, they can begin producing and installing it into the various machineries. The only problem then is time, the more time they have, the more they can prepare. If not given enough time, the results will diminish. Another factor is who the leader of the Institute is, with Killian needing more time to prepare it than Marcus.
The Capital Wasteland
How much help can we expect? The Lost Hills, Mojave and Montana chapters are too far and too out of touch. The guys in Chicago are having Enclave troubles. The Florida chapter is busy "fighting crocs" or whatever... Guess we are all you got.”— Paladin Maxson
- As the player arrives in River City, known as Rivet City in Fallout 3, they will be immediately greeted by the voice of Three Dog over the radio. Walking through the city, the player will eventually be directed to the city's security chief, Harkness. While he can be convinced to send supplies for aid, Harkness refuses to send his men to the Commonwealth. However, he does make the suggestion of speaking with the Brotherhood of Steel. Whether by driving or crossing a bridge in the city, the player must go to the Citadel and speak with Elder Sarah Lyons. Sarah is initially unsure but with a little help from Paladin Maxson, she can agree to aid the Commonwealth, there's only one problem: the Brotherhood Outcasts.
- The Outcasts have become increasingly hostile against the Brotherhood, even launching raids against the Citadel. While these raids have been unsuccessful, the Outcasts are more powerful than some in the Capital Wasteland realize and Sarah refuses to leave the Citadel undefended while they are attacking. While the player is sent to Fort Independence to try to negotiate peace, it should be very clear that Protector Casdin has no plans on stopping their attacks, believing that Sarah has crossed the line with her trades and giving people Enclave technology.
- The Outcasts offer a deal to the player to help the Commonwealth in exchange for the player’s aid against the Brotherhood, forcing the player to choose which side to join. The Brotherhood has Vertibirds and numbers while the Outcasts have more experienced and well equipped soldiers. Telling Casdin you are siding with the Brotherhood will immediately turn him and the rest of the Outcasts hostile, but Brotherhood reinforcements will come in to help the player. Choosing to help Casdin will result in the player returning to the Citadel and planting a bomb that will allow the Outcasts to enter the Citadel.
- When the fighting is over, either Casdin or Lyons will be dead and Maxson will be held by the Outcasts if they were sided with, Casdin stating he needs some "re-education". Afterwards, either Casdin or Lyons, whoever is alive, will take the player to the Citadel’s basement to show them the Brotherhood’s greatest weapon, Liberty Prime. While Prime was destroyed by the Enclave, the Brotherhood has successfully repaired the robot’s internal machinery, leaving just its massive armor and software bugs in need of repair. Maybe if there were two allies with plenty of metal and technology experts...
Those Ronto bastards came out of nowhere and attacked without warning in the middle of the night. If they think we're going to just lie down and die, they have another thing coming.”— Ford
Gunfire is the first thing the player will notice upon approaching Detroit, and is something the player will continue hearing throughout their stay. Detroit has been under attack by Ronto for days and it's mostly because Ronto hasn't taken them seriously that they've lasted this long. With some convincing (which is easier for a ghoul), the player can meet the ghoul leader of Detroit, Ford. Angered by Ronto's attack, Ford is more than willing to get vengeance against them by aiding in the defense of Commonwealth. However, they must defeat the soldiers here first. The player can help in a variety of ways, including strategizing, fighting, maintaining equipment, boosting morale, etc.
- If the player is unable to get the counter for Ronto's EMP weapons, for example idiotically turning Wilson hostile, New York may be one of their greatest allies. The soldiers of New York are hardened veterans, excelling in guerilla warfare and using conventional weaponry. The only problem is, they are one of the few factions not so willing to join in the fighting. Convincing may require everything from Speech, making deals between New York and other factions, and revealing a Ronto plan to assassinate New York's leader, Alexander
- While the Pitt does have some military power, in the form of the Pitt raiders, that is not what makes them a powerful ally. Rather, it's their large supply of steel that is extremely useful to the war effort, allowing for the other factions to craft weapons, help repair Liberty Prime, and constructing androids. While Marie is willing to temporarily increase the amount of steel she exports, she will also increase the price of the steel. Convincing her to lower it is difficult, although a Pitt raider's suggestion of having Paladin Maxson speak with her makes her slightly easier to convince.
- Havre de Grace is well known for being the home of Gamma Defense Incorporated. While getting them to join the war effort is easier than any other faction, getting them to do it for free is another matter. While they have a variety of packages to choose from, the full package costs 30,000 caps. Even if the player does a variety of favors for them, the cost of the full package will only be reduced to 15,000.
Part 3 - The Finale
- With as many allies as possible recruited, the player must enter the final battle. The final battle varies quite a bit depending on the status of the EMP weapons and the allies that have been recruited. When the battle begins, the player can choose to either join the fight directly, or attempt a stealth tactic to kill Logan directly. Once Logan is killed, the battle will turn in the allies' favor and Ronto will begin to retreat. After the battle, the different factions will meet, along with Gerard from Ronto, and discuss what to do with Ronto. The options include: destroying Ronto, allowing Gerard to lead and restore Ronto, and the player possibly leading the faction themselves.
- When the fate of Ronto is decided, the endings will play. Endings range from a permanent alliance forming between the factions that fought in the war, and possibly Ronto, and the beginnings of a new government, hostilities between certain factions such as the Outcasts and the Commonwealth, or things, for the most part, returning to how they were both the war. Endings for the individual locations range even greater. When the endings finish playing, the game continues one month after the battle, with new side quests and locations available depending on how the story ended.