Blake Lively has signed on to star in the adaptation of Liane Moriarty's bestseller The Husband's Secret.

The actress will also executive produce the CBS Films project from the author behind this year's (16) hit TV drama Big Little Lies.

The film, which has yet to secure a director, will revolve around Lively's character Cecilia Fitzpatrick, whose perfect life is shattered when she finds a letter written by her husband, in which he details what he wants her to do in the event of his death.

"She inadvertently discovers that her husband has been keeping a secret from her for years... a secret that leads her to realize that her life is built on a foundation of lies and murder," a press release states.