I’m a total sucker for films exploiting the amnesia trope, as hackneyed as it is (if it’s good enough for The Bold and the Beautiful, it’s good enough for me!). There’s something immediately engaging in the character and audience sharing the same predicament: not knowing the specifics of the events that preceded the film’s beginning, and at the whim of the information supplied – and denied – by the cast around them. For a while, Before I Go to Sleep seems like it’s going to leverage the power afforded by the amnesiac bond it forms between its audience and protagonist … before going to sleep itself, wading into unrewarding, outlandish twists and squandering the promise of its premise.

Said protagonist is Christine (Nicole Kidman), afflicted with a rare form of amnesia after an accident years prior. Every morning she awakes with no memory of the last dozen years; she’s forty years old but thinks she’s still in her twenties (but, hey, she still looks like Nicole Kidman, so it’s not a total bust). Her husband Ben (Colin Firth) patiently explains that they’ve been married for fourteen years, with dozens of photos of their wedding and life together stuck up in their en suite.

This ain’t 50 First Dates, though, and the plot soon thickens. There’s a phone call from a mysterious doctor (Mark Strong) who directs Christine towards a camera – hidden away from her husband – on which she’s been recording her private thoughts daily. It becomes clear that she’s faced with two competing narratives – the story presented by her husband of easy domestic bliss, or this psychiatrist who urges her to keep their meetings quiet from Ben and informs her that her amnesia sprung forth from a brutal, unsolved assault rather than an accident. Much like Guy Pearce in Memento, she’s unsure of what to trust – even her own video recordings may be untrustworthy.

At about this point in the film, I figured that director/writer Rowan Joffe would use the amnesia as a springboard to contemplate the way age slips away from us and – as we watch Christine squirrel away fearfully in the bathroom to record a video without her husband’s knowledge – perhaps a representation of an abusive, controlling relationship.

And at about this point, the film’s potential dribbled away. We shuffle through a conga line of characters delivering huge chunks of exposition to Kidman – justified by her amnesia, sure, but boring nonetheless (at one point Firth complains, “I’m tired of explaining!” and I couldn’t have agreed more). That amnesia, meanwhile, becomes Convenient Movie Amnesia, with memories returning at just the right moment to facilitate the storyline. The third act escalates with a Big Plot Twist that’s not grounded in character (admittedly, Kidman’s adolescent vacancy doesn’t help matters), narratively implausible and quite unsurprising (again with the admittedly – there’s only so many possibilities presented in such a small cast).

I wasn’t necessarily expecting a plausible narrative that stands up to some – or, really, any – scrutiny from an amnesia thriller. Gone Girl, for example, is earning plaudits all over the place but pull on the wrong string and its plot falls apart. I have no problem with a film riddled with plot holes provided it brings something to the table; say, pulpy entertainment, a compelling subtext or, heck, just good old fashioned visual panache.

But Joffe is no Fincher. There are glimmers of light in Before I Go to Sleep – visually there’s a memorable, if slightly-on-the-nose shot tracking past infinite aisles of blank female mannequins – but it’s overall a disappointment. Especially disappointing is how those aforementioned promising concepts are under-developed; a potentially nuanced take on controlling relationships is subsumed by a disturbing shift into domestic violence in the final minutes. Frankly, I kinda wish I could forget this film.