Living together begins to take its toll on Kelly and Brandon's relationship. Donna asks David to move back in with her at the beachfront apartment, but with a stipulation that they sleep in separate rooms and that he doesn't tell her parents. Meanwhile, Steve has a couple of run-ins with Carly Reynolds - a young, overprotective, sarcastic, single mother with a six-year-old boy named Zack - who Steve wants to know more about.