Nicole Kidman has to remember who tried to kill her in the first trailer for “Before I Go to Sleep”, but she has to figure it out before bedtime, otherwise she'll forget, TheWrap said.

The preview for the psychological thriller outlines the set up for the Studio Canal film, in which Kidman plays a woman with amnesia after being found nearly dead, with repeated blows to her head.

Colin Firth stars as her husband, who appears to be keeping secrets about her past, while Mark Strong plays the doctor trying to help her sort through her memories in order to discover those secrets.

Whether or not either of them is responsible for her daily dose of amnesia, Kidman has to remind herself “don't trust anyone” before she falls asleep.

“Before I Go to Sleep,” written and directed by Rowan Joffe (“Brighton Rock”), hits theaters on Sept. 12.