An international criminal spells trouble for the agents of Britain's Department Z, in this suspenseful mystery from an Edgar Award–winning author.

Marius Krotz is notorious for his ability to cause a stir. A former revolutionary turned right-hand-man to the king of a small European country, he is feared as much for his unscrupulous manner as for his dangerous past. He's planning something big, and intelligence agencies across Europe have him in their sights.

Department Z is on the case, led by the infamous Arran twins and new recruit Jim Burke, and this time they're pushed to their limits. Department Z must be prepared for unknown dangers beyond anything they have encountered before—and it's a race to take down Krotz before he can cause irreversible international damage.

Thunder has been rolling in Europe—but can Department Z avoid the lightning?