Carnival 1933: Gereon Rath has a blast at the Cologne carnival.
The next morning, he wakes up with a hangover, the wrong woman by his side, and a phone call from Berlin: The Reichstag is on fire! Immediate recall of licenses!

Rath "inherits" his next case from his boss, Wilhelm Böhm, who falls out of favor and is pushed to the sidelines by the Nazi police chief.
The case involves a homeless man found murdered in Nollendorf Platz.

This man's story leads back to the past, specifically to March 1917, when German soldiers left scorched earth in northern France during Operation Alberich.
Rath investigates the case, but something keeps getting in the way of his investigations. As for his preparations for his wedding to Charlotte Ritter, it is the least of his problems.