"Clueless" is the fifteenth episode of the second season of House and thirty-seventh overall, which premiered on Fox on March 28, 2006.
The episode's cold opening begins with Maria being violently grabbed and carried to the bedroom by a man.
House is convinced that the symptoms are typical of heavy metal poisoning, but none of the tests confirm that diagnosis.
House decides that Maria must be poisoning Bob, as any heavy metal that could enter his system by other means has been tested for.
House enters the restroom just as she is leaving the stall, takes hold of her hands and apologizes for his inability to properly treat Bob.