Upon entering, you will see a group of Dead Horse tribals; one of them will ask why you are present in the cave.
There are two main rooms in the cave; a small Dead Horses camp area with a few tents, and a larger cavern where Joshua Graham resides. The larger room, in which Joshua Graham is found, contains a workbench with a workbench crate near it, and a reloading bench.
The rear exit of the cave leads to an enclosed clifftop area, containing a Dead Horses camp area and in the far corner, one of the six Survivalist hidden caches.
There is a significant amount of cave fungi that can be harvested throughout the cave.
If you have the Wild Wasteland trait, a man called Two-Bears-High-Fiving will leave the cave and pump his fist in the air before you enter it for the first time. Afterwards, he will immediately return back into the cave and resume his normal routine.
There are several of the .45 Auto pistols on the desk where Joshua Graham is sitting, which can be stolen, resulting in a loss of Karma. It is possible to steal four of the guns (they are in low or medium condition); the rest are just scenery items and thus cannot be taken.
There is also a .45 Auto pistol in good condition in a footlocker behind Joshua.