Kalmann is back! But he's already in trouble; in an interrogation room at the FBI headquarters in Washington, no less. All he wanted to do was visit his American father, but the loveable sheriff of Raufarhöfn got himself mixed up in the January 2021 Capitol riots. Thanks to sympathetic FBI agent Dakota Leen, he's soon on a plane home. But not before she informs him that his grandfather was on a blacklist, suspected of spying for the Russians during the Cold War. Back in Iceland, there's a murder and one heck of a mystery to unravel. And what role does a mysterious mountain play in all this? Somehow Kalmann never loses heart. There's no need to worry; he has everything under control.