Starts as a female comedy version of Prison On Fire, blending into a take on Magic Cop. The actresses (who play female prisoners) in this large ensemble cast are credited (in Chinese) as they appear, and the story keeps shifting focus until the serious ghost-horror stuff starts about 2/3 of the way through.

Several things are unexplained. For instance, why the prison guards are dressed as police (including Stanley Fung, doing his usual Inspector role). And the crimes for which the girls were imprisoned are never even alluded to, let alone named.

Not that this is hugely important, in a light'n'sexy comedy cum ghost- exorcism flick. La Amy is (understandably) the butt of boob jokes in all her films, but she seems to cop more than all the others put together in this one. And if the cat fights and clothes-ripping isn't enough tits'n'ass for you, there's a generous helping of group shower scenes and guys watching through a telescope in a tree. Blackie picks up a music box, which brings ghost Jane back. Jane is a playful little girl spirit, and innocently starts a few fights, which begins to scare both inmates and guards. Meanwhile, three guys (who's involvement in the story I really couldn't grasp) try to get into the jail and to the girls, with some encouragement.
And Inspector Feng appears to woo Pei, but he really wants he to perform "religious service" (exorcism). By this stage, the cruel madam/evil ghost is stirring things up. Things get rather hard to follow, and it's far from light comedy at the end.
Still, an offbeat and quite entertaining blend.