What the Dead Know is a crime thriller by the American writer Laura Lippman, published in 2007.

[1][2] The story, set in Baltimore in 2005, is about an investigation into a woman who claims to be Heather Bethany, a girl who had gone missing thirty years before.

Reviewers saw What the Dead Know as a success both as a well-crafted mystery and as an emotionally powerful novel.

[3][4] The Guardian described the novel as a "realistic and poignant detailing of emotional hide-and-seek, ... an excellent mystery and a thoughtful exploration of the nature and effects of grief and loss.

"[6] Janet Maslin of The New York Times praised What the Dead Know as "an uncommonly clever imposter story", "three-dimensional", and worthy of reading a second time — "You read it once just to move breathlessly toward the finale.