Inspector Gereon Rath uncovers a dangerous web of shadows when investigating 1929 Berlin's seedy underbelly.

Rath tries to interrogate König further regarding the missing film reel, while a Russian revolutionary's location is revealed by an informant.

The freight train reaches Berlin, tempers ignite in Charlotte's household, and aspiring inspector Janicke makes use of a hidden skill.

The May Day stand-off between communist protesters and police explodes in violence. Inspector Bruno has a way to uncover Rath's intentions.

Kardakow realises that his initial instinct was correct, a photo enlargement reveals two leads, and Rath and Charlotte receive key intel from a colourful character.

Rath makes a confession to a priest, and later to Wolter. Charlotte persuades medical student Rudi to perform a secret autopsy, which uncovers a vital clue.