In an overcrowded Stockholm underground station a stressed father makes the split-second decision to entrust his older son to a kind stranger. Son and stranger vanish, never to be seen again.

Many years later the missing boy's brother, Joel, also disappears in suspicious circumstances. His wife turns to Danny Katz – an old friend – for help. But Katz isn't the only one seeking Joel, and as he digs deeper, the case takes a dramatic new turn.