House is faced with a problem he may not be able to solve and Stacy returns.

House's wheels start turning when a pro-cyclist admits to taking performance-enhancing drugs.

A patient with AIDS stalks House to get him to take his case; House and Stacy stalk a mouse in her attic; and Cameron faces a health scare of her own.

While House's staff tries to diagnose a woman whose uncontrollable muscle flailing caused her to crash her car, House and Stacy try to resolve their relationship issues once and for all. Cameron refuses to take her HIV test, wary of the results.