Lucy Harper has a talent for invention…

She was nine years old when her brother vanished in the woods near home. As the only witness, Lucy’s story of that night became crucial to the police investigation. Thirty years on, her brother’s whereabouts are still unknown.

Now Lucy is a bestselling thriller writer. Her talent for invention has given her fame, fortune, and an army of adoring fans. But her husband, Dan, has started keeping secrets of his own, and a sudden change of scene forces Lucy to confront some dark, unwelcome memories. Then Dan goes missing and Lucy’s past and present begin to collide. Did she kill her husband? Would she remember if she did?

Finally, Lucy Harper is going to tell us the truth.


Cross her heart.
And hope to die.


One of the most unsettling—and unforgettable—heroines I’ve ever met

Shari Lapena, New York Times bestselling author of The Couple Next Door

To Tell You the Truth is a spellbinding book about a missing child, and about the life of a writer. Bold, suspenseful, and impossible to put down. This one will stay with me for a long time

Samantha Downing, Sunday Times and USA Today bestselling author of My Lovely Wife

A dark, tense and very clever read with one of the best unreliable narrator’s I’ve ever come across. The plot is original and so compelling I couldn’t turn the pages fast enough to find out if Lucy Harper was telling the truth. This is an outstanding thriller and Gilly Macmillan is at the top of her game

Claire Douglas, Sunday Times bestselling author

Another fabulous read by Gilly Macmillan. When the main character is a thriller writer, you just know you’re in for the twistiest of rides!

Lesley Kara, Sunday Times bestselling author of The Rumour