This review contains spoilers

Christine Lucas (Nicole Kidman) wakes up next to a man with a wedding band. Carefully prising herself from bed, and treading lightly so as not to wake him, she makes her way to the en suite bathroom. She is surprised when she sees a grown woman’s reflection in the mirror and a wedding band on her own finger. There are photographs of her and the man she shared a bed with, taped to the wall. Yellow Post-it notes tell her that his name is Ben (Colin Firth), and that he is her husband.

This is how Christine Lucas begins every day: unsure of herself, where she has woken, and with whom she has slept the night before. She takes breakfast with a side of memory 101 before her husband goes to work. Shortly after, the telephone rings. A Dr Nash (Mark Strong) tells her to look for a video camera, kept in a shoebox at the bottom of her wardrobe. They are doing some work on her memory, without her husband’s knowledge. Christine is confused and scared.

This is the set up for Before I Go To Sleep, Rowan Joffe’s film adaptation of S J Watson’s crime fiction novel of the same name. Though the premise may bring to mind the rom-com 50 First Dates (2004), Before I Go To Sleep is a true generic gem. Never straying from the margins, throwing plenty of red herrings into the mix, sustaining tone and tension throughout, it also finds time to reflect on and re-write the classic narrative device of gaslighting.

The term harks back to Patrick Hamilton’s 1938 play Gas Light and the two film adaptations it spurred: Thorold Dickinson’s largely-forgotten 1940 British version and the far more memorable 1944 star-laden thriller directed by George Cukor, both titled Gaslight. The premise is one of psychological manipulation: making one’s victim (wife) doubt their (her) own sanity, perception and memory of past events through denial and trickery.

Aided by her amnesia, Christine’s oppressor doesn’t have to work very hard to exorcise the full extent of his narcissism. What’s intriguing though, is how Christine – perhaps the most helpless of all the screen types to suffer gaslighting – uncovers the truth.

It is no secret that mainstream cinema has, historically, been unkind to women. Alfred Hitchcock’s Dial M For Murder (1954), Jack Clayton’s The Innocents (1961) and Roman Polanski’s Rosemary’s Baby (1968) spring to mind quickly. Surprisingly, of these three, it is only Hitchcock who lets the truth save his leading lady (Grace Kelly). Miss Giddens (Deborah Kerr) and Rosemary Woodhouse (Mia Farrow) met less fortunate ends. I’ve made mention of the actresses because it’s also worth saying that, from Ingrid Bergman all the way to Nicole Kidman, screen women who become the victims of gaslighting are also very often icons in their own right. Surely it is not coincidental that these films were also all directed by men. Perhaps this is owing to the power dynamic necessarily built into the structure of the relationship between director and actor: much like gaslighting, it is predicated upon narcissism.

But for Christine, gaslighting goes far beyond the dimming of lights. Christine’s condition is the result of a full-scale physical attack. The person (man) who has caused this amnesia-inducing trauma, however, is unknown to her. Paradoxically, at the same time, she is the only person who can solve the mystery since the truth lives, somewhere, inside her memory. The subtle alteration of one key element from the text – instead of keeping a written diary, Christine keeps a video diary – turns Kidman into a sort of internal genre sleuth, as Joffe likens cinematic gaslighting to the very process of filmmaking itself.

He blends seamlessly from that first scene where Christine awakens, with unexplained facial bruising, into the pre-recorded world of her diary entries. The Christine with whom who we are presented is the detective; every version of herself that she then watches – though they all appear to be her – is like a stranger. It is not herself that she distrusts, though, so much as the device. All that Christine knows is that she was given the camera by a man (Dr Nash) and is to hide it from another man (Ben). The video diary shows her that it is filmed in secret, that she is the sole author. Due to her condition – the literal amnesia that extreme actions of gaslighting have induced – she can never be sure that it has not been edited by that same assailant, the man who ‘did this to her’.

Throughout the film, the trauma Christine has suffered is referred to as a thing that has been done to her by someone else. Christine is the victim (object) who has suffered at the hands of another (subject). The reason she was attacked and is continuing to be abused is her refusal to be emotionally and physically bound to that man, as well as because of her infidelity to another man. In her assailant’s eyes, she has simply performed her devotion to him – she was never truly devoted.

There are limits to how much control the men directing can exert.

The film plays out its three-act structure through the three stages of gaslighting. First is the idealisation stage where Ben puts on his best performance: love, devotion, and charm. Then, once Christine is convinced of his honesty and innocence, devoting herself to him, he turns and enters the devaluation phase. He is cold and calculating; he no longer wants to engage with the performance at all because he is not getting everything that he wants. It is during this phase that he edits Christine’s video. Finally, comes the discarding phase, where the individual has become a worthless inferior to the narcissist.

Mike reveals himself. He is tired of pretending to be Ben for Christine’s benefit. They either leave the hotel where the trauma took place as ‘Christine and Mike’ or they don’t leave at all. No longer the object of his affection, Christine must commit to the role entirely or he will kill her.

Though Before I Go To Sleep is Christine’s story, it is men who control everything. She is attacked by a man, prompted to investigate her own story by a man, and, at the very end of the film, is incapacitated, literally lying in hospital unable to get up, facing a stream of men: Dr Nash, the real Ben, and her son Adam. What she has awoken to remember is her duty as wife and mother – the neglect of which was what got her into this whole mess in the first place.

Christine’s trauma, amnesia and gaslighting were all, in a sense, self-inflicted. Her role was to be mother and wife: dutiful, doting, and faithful. Joffe exposes the true terror in that screen history of gaslighting: even when the reveal says the woman has been telling the truth, that she has had horrors ‘done to her’, her fate is still, ultimately, her fault. Performance is deceit. The actress must be punished.

What then of Joffe? He revels in what he reveals. Though genre relies on audience expectancy, its knowledge of tried and tested visual and narrative tropes, film doesn’t have to continue showing men gaslighting women.

But, of course, it’s a lot easier, and more plausible, to trick, manipulate and rewrite the memory of people who have already been conditioned by patriarchal society to doubt themselves.