Well, you’ve got to give it this: Never before have the erotic possibilities of dentistry been so fully explored — no doubt because few dentists look like Julia Ormond, and fewer still look like her and practice in a London prison. That’s where she meets jailbird Tim Roth and his intense gaze, and where the closeness fostered by fillings proves too heady for them both. But there’s more than just steamy assignations in Underground loos for Rachel and Philip; other cons have different plans for them. Oddly, although Captives contains some genuine tension, it keeps dissolving in a sea of somnolence. This is one thriller you don’t want to watch from too comfy a couch. B-