Carry on Dancing

Cheung Sheung and Tze Ngor are twin sisters. Tze Ngor is a lunatic and stays in a mental hospital. But out of a madcap incident, Cheung Sheung is cheated into the hospital, exchanging identity with her insane sister. The mad house is lived by all kinds of weirdos. The game is that Cheung Sheung will stay in the hospital only for a while. But strangely enough, she gradually becomes more and more ease with the way of life in the hospital until one day, she's forgotten what life is like...