Reid Underwood's terminal is found in the lower west section of the cargo hold of Mothership Zeta in the Fallout 3 add-on Mothership Zeta. It details Reid Underwood's acquisition of the MPLX Novasurge (plasma pistol prototype) from the hands of the conspiracy that became the Enclave  [verification needed], and how it ended up in Underwood's safe.
Log Entry 4-11-2063Edit
They think we're stupid; that we have no idea what they're up to. But we know. Barbed wire topped fences and security cameras be damned! We'll get the truth to come out if it's the last thing we do! The conspiracy has to end, and we will be the ones who drag it from the shadows and cast it into the spotlight for all to see. They deny everything. They deny the place even exists! But here we are, faced with armed guards who patrol the dunes and robotic sentries calculating our every move. They're careful, but not careful enough. I've found a loophole, a way in, and I mean to exploit it soon.
Log Entry 4-15-2063Edit
We've done it! We have it in our hands! The smoking gun... the evidence we need to prove that everything they've told the world is a lie! Now let's try to see them weasel their way out of this one and make petty excuses. The only reason they've been so successful this long is because of the lack of proof on our part. Now that's all over. As soon as the coast is clear, we're bringing this thing to the press. But for now, we need to lay low. No telling how long it'll take before they discover how we did it.
Log Entry 4-16-2063Edit
They're closing in! How did they find out? What did we miss? I thought we'd covered our tracks, but there must be something we'd forgotten. The security logs were completely erased, the inventory files were rewritten... that only leaves Doctor Morley! That bastard! He approached us saying he wanted to crack The Conspiracy wide open, and all the while he was playing us like fools! He just wanted to expose us, to bring us out into the open so they could eliminate us! Well, it's not going to work! They'll never find us and they'll never get their hands on the item!
Log Entry 5-01-2063Edit
Banks is dead. Combs is dead. I'm the only member of Quaere Verum left. I'm not certain how much longer I'll be safe here. I'm placing the item inside a specially constructed safe with a remote lock trigger. It'll take a damn genius hacker to get into this terminal and the safe can withstand anything they throw at it. Tomorrow I take the terminal and the safe, and I'm going to bury it out in the desert where they'll never find it. Hopefully, one day, someone else will discover the item and realize that they hold the key to unlocking the truth. All they need to do is succeed where we have failed. Good luck to us all.