Uncle Bill has left on an expedition and entrusted the apartment to the player, along with the animals already living there. Shortly after settling in, the building's janitor arrives with a lost puppy—nobody knows who it belongs to, so it's the player's responsibility until the owner is found. The Sims 2: Apartment Pets is a pet-care game in which neighbors, visitors, and the janitor continue to drop off animals for temporary care throughout the game, building up a rotating cast of creatures that each need feeding, attention, and affection.