In Hong Kong, at a masked ball party, a greedy rich man pretends he has lost a diamonds ring, blaming a young girl for the theft, and demanding that she pays him for the cost. Later, the Chan sisters Chan Meiling and Chan Meiyu dress in black leotards to look like black cats in the darkness of the night, leave their luxuriously villa, called The Rose Garden, and start robbing from the rich people that they know are fraudsters or otherwise evil. Even if they give the profits to the poor, their actions are causing alarm in the high society. The police suspects come to nothing, as one sister pretends to be the other, on occasions, and they act alone. An insurance detective, Cheung Manfu (PATRICK TSE YIN) comes to investigate the case, follows the two ladies, and tries to arrest them several times, but fails, namely because their villa has secret underground passages. For each new daring robbery, the sisters leave behind a black rose, signing their action.