Caching in with Three Dog

 refers to an unmarked quest in Fallout 3.

This quest can be activated after you discover your father's whereabouts from someone other than Three Dog, or by using a successful speech check to have him tell you where your father is. This is an alternate quest reward if you decide to complete the Galaxy News Radio quest anyway. After you finish the quest, Three Dog compliments your dedication and then gives you the key and map location to his personal weapon stash at Hamilton's Hideaway.

The cache is behind a cell door in the northwestern-most area, behind some rubble.

Reward

 * Guns and Bullets
 * Mini Nuke
 * Stealth Boy
 * Combat Armor/Metal Armour
 * Combat Helmet/Metal Helmet
 * Power Fist
 * Assault Rifle