Three Dog has the Cache Key

So, if you didn't know, there's a weapons cache in Hamilton's Hideaway which can only be opened by a key you get from Three Dog. The only way to get the key is, during the GNR quest, to have either found your dad already, or pass a speech check which is relatively difficult for such an early point in the game. Didn't do either? Too bad. You can never get into the weapons cache.

Now let's be honest, that's stupid. You might not even know that that's the case, and be left scratching your head as to why there's a locked gate in a random location that you can never open with a ton of loot behind it. But fear not, my friend. With this mod, Three Dog now has the key on his person, rather than magically conjuring it from thin air through dialogue - this is Fallout, not the Elder Scrolls, after all. This means you can pickpocket the key from him to get into the cache if you missed your opportunity to get it in the quest. Or, you could kill him for it. But don't do that. Killing is mean.