When Matthias Trockland, who turned witness for ZERV, is found dead, ZERV West Commissioner Peter Simon and Karo Schubert from the Berlin homicide squad work together to solve the mystery surrounding Trockland's death.

When ZERV officers find a large cache of banned weapons in the decommissioned NVA military site, Simon and Karo presume that Trockland may have been killed because he was pursuing the illegal NVA arms trade.

Böttcher's death forces a distraught Gärster to turn himself in; in ZERV custody, Simon makes an unauthorised deal with Gärster without the knowledge of his boss; Karo makes a shocking discovery about her father.