Set in a dim, dingy tenement apartment, The 24th Day is a stifling two-hander that waffles through a succession of dutiful reversals, only to reveal itself as an insultingly didactic safe-sex PSA. Adapted by Tony Piccirillo from his stage play (which starred TV doctors Peter Berg and Noah Wyle), the film begins with a pickup: Smugly poised Dan (James Marsden) goes home with rumpled, mumbly Tom (Scott Speedman), and the flirtatious banter gets awkward quickly. It transpires that the two had a one-night stand a few years back; Dan, apparently a slut, forgot. In the ensuing fog of embarrassment, Tom suddenly overpowers Dan, ties him up, and forcibly extracts a blood sample. Tom claims he’s HIV-positive (he found out 24 days ago, hence the title) and Dan is the only man he’s ever slept with. Dan maintains he’s been tested many times and is negative.

And so begins a Death and the Maiden tango of culpability and vengeance in which the mantle of victimhood is lobbed back and forth like a ticking grenade. (There are also similarities to Richard Linklater’s Tape, another theater-based chamber piece.) But the all-important dynamic between captor and captive never ignites. No amount of fidgety editing and anxious soundtrack atonality can distract from the creakingly implausible scenario (Marsden’s Dan is an almost comic exemplar of uncharacteristic hostage behavior). When at a loss, the script defaults to mawkish confessional monologues or, worse, belabored pop-culture riffs, forcing kidnapper and hostage to take time out from their designated roles to discuss their favorite Charlie’s Angel.