The "Before I Go To Sleep" film adaptation starring Nicole Kidman and Colin Firth will be hitting cinemas on September 5. Even if the flick is only less than a couple of weeks away from its release date, SJ Watson, the author of the psychological thriller, is still incredulous of the success of his first book.

Knowing how the odds stack up for debuting authors, SJ Watson was ecstatic when his book was finally accepted, published and released after toiling on it for five years. His joy and success compounded when his book became a bestseller. However, despite his novel's success, he did not realize it would catch the producers' attention - and much to his delight it did.

Now "Before I Go To Sleep" film adaptation starring Nicole Kidman and Colin Firth is just several days shy of hitting theaters.

The Independent divulged that the author was doing part-time stints as an audiologist at the NHS in UK when his novel landed on the bestsellers' list. According to him, working at the hospital thrice weekly, evaluating infants and kids with hearing disabilities was relatively easier compared to the daunting task of penning "Before I Go To Sleep" (with Nicole Kidman and Colin Firth in the lead roles in the movie adaptation).

The "Before I Go To Sleep" film adaptation features Nicole Kidman (in the role of Christine Lucas) and Colin Firth (her doting hubby Ben) as a dubious couple. The mystery that entwined them and permeated every thread of their relationship sets the stage for the events that unfolded, as seen from the perspective of the amnesiac wife who has lost her memory, including her life with her husband, reported The Independent.

The classy psychological thriller is among the must-watch book-to-movie adaptations, Metro said. Rowan Joffe directed the film. It also stars Mark Strong as Dr. Nash, who plays a critical role in Christine's life. Whether or not he would help her solve the mystery involving her hubby, viewers will find out the truth when the film opens on the first week of September.