April 1955 - in a few days, the Federal Republic of Germany will sign an official Peace Treaty with the Allies and assume full sovereignty over her affairs. The nation looks to a bright future, but ghosts of a darker past linger unquietly - not least among those charged with her defence. In West Berlin, celebrations are muted by the enclave's continuing occupation and a string of murders whose investigation, rigorous at first, appears to be stalling...