Pursuing a gang of robbers, Stacy receives a mild concussion in a shoot-out, and after being discharged from hospital, decides to take a break to go and visit her sister. But driving through a fierce thunderstorm and still in a slightly dazed state, she is involved in a minor road accident which leaves her with amnesia, and is taken in by a passing motorist who claims to be a local doctor. Meanwhile, Hooker and Corrigan become concerned at Stacy's sudden disappearance, and investigate a break out from a mental hospital where two dangerous patients have escaped - and unbeknown to them, one of the escapees is the man posing as the doctor who has taken in Stacy.