Combination murder mystery and sex drama features four guys, one girl, and their rock band becoming entangled in the randy South of France, which means full-frontal male as well as female nudity, homosexuality, brother-sister incest, orgies, blackmail -- all the things you'd never see in such a summery teenage wrapper in the United States. Even the killing seems like just one more erotic device. Lizzie Brochere stars as the duplicitous sister, Lucie, with Arthur Dupont, mostly in flashback, as her brother, the murdered Pierre. Codirected by actor turned filmmaker Jean-Marc Barr with writer Pascal Arnold, and set gorgeously in Provence. French title: Chacun sa nuit (95 min., 2006).