Sometimes, as Tammy Wynette so ­plangently observed, it’s hard to be a woman – and this particularly increases if you happen to be a female character in a thriller, whether literary or on-screen. For a start, if you’ve made it beyond the first few minutes (or pages) without horrible damage – if you’ve avoided being the body found in mysterious circumstances – then you are destined to suffer (whether as detective’s spouse or even detective) and be put in imminent peril. With Before I Go to Sleep, it’s as if all the symbols on the fruit machine aligned at once. A woman (Nicole Kidman) wakes. At first, she’s a little disorientated, not least because there’s an unfamiliar, if handsome, man (Colin Firth) beside her. When she gets