Rescue Cats is one of the two Character Challenges for the Fireman (the other being Extinguish BBQ Fires) in LEGO City Undercover, and the sole Character Challenge for the Fireman in LEGO City Undercover: The Chase Begins.
In LEGO City Undercover, once the Fireman Disguise has been unlocked, the player can rescue cats for a Gold Brick. There are 17 cats to rescue throughout the city and they are seen with black fur.
In LEGO City Undercover: The Chase Begins, there are 28 cats to rescue, 4 in each district. Unlike the original game, these cats are ginger.