Knock Knock

Brought to you by Penguin.

Set over three explosive days, this is compulsive, heart-pounding storytelling that will keep you on the edge of your seat.

He thought she was safe. Then the past came knocking.

Seventeen years ago, Inspector Ewert Grens was called to the scene of a brutal crime. A family had been murdered, with only their five-year-old daughter left behind. The girl was placed under witne...