Before I Go to Sleep Nicole Kidman, Colin Firth, Mark Strong. Directed by Rowan Joffé. Rated R. Opens Friday.

Anterograde amnesia has already served as the basis for one masterpiece—Christopher Nolan’s ingenious Memento (2000)—so it would be unduly optimistic to expect another. A plot that makes a lick of sense, however, doesn’t seem like too much to ask, and that’s more than Before I Go to Sleep can manage. Adapted from S.J. Watson’s best-selling novel and directed by Rowan Joffé (Brighton Rock), this risible thriller squanders a promising setup and three superb actors, building to third-act revelations that leave the viewer with no option but to sit there with painfully furrowed brow repeating, “But … but … but ...” If it didn’t take itself so seriously, that might not be such a problem, but trashy fun isn’t what it’s offering.

Like Memento’s vengeful protagonist, Christine Lucas (Nicole Kidman) knows who she is and can recall her distant past, but has suffered a brain injury that prevents her from retaining any new memories. Going to sleep triggers the reset button, and she awakes each morning with no recollection of the previous day. Her kindly but distant husband, Ben (Colin Firth), helps her manage this maddening condition, while also hiding certain key details of her life, ostensibly for the sake of her own mental health. Unbeknownst to Ben, however, Christine’s shrink, Dr. Nasch (Mark Strong), has encouraged her to start keeping a video diary that will allow her to construct some sense of continuity. Which of these two vaguely sinister men is taking advantage of Christine’s fragile condition, we’re meant to wonder, and to what foul purpose?

The answer, as they say, may surprise you, mostly because it’s so damn ludicrous. Kidman is no stranger to silly pulp, having starred in Malice more than 20 years ago. But that film had a firm grasp of its own absurdity, a quality that Before I Go to Sleep sorely lacks. Joffé ladles on the solemnity with a trowel, and has seemingly instructed all three of his lead actors (especially Firth) to simulate the aftereffects of heavy sedatives. While there’s an undeniable pull to work out just what’s going on here, curiosity can only sustain a fundamentally dumb movie for so long.