Inspector Fritz Dellwo has a special goal: He takes part in the Messe-Frankfurt-Marathon. To achieve his ambitious goal of running in under four hours, he joined a running group led by veteran trainer Henry Danquardt. But the night before the big event, after the traditional Festhalle noodle party, Dellwo is called to the presidium. The criminal Petar Gricic, whom he once put behind bars, has escaped from prison. Dellwo ignores his colleagues' warnings and insists on being on the starting line the next morning. The catastrophe happened during the start. A young Swedish runner is struck down by a bullet and dies from his injuries shortly afterwards.
Charlotte Singer finds out that thesniper shot down from a church tower and was actually aiming for Dellwo, who had started near the Swede. The search for the escapee Gricic, who once swore eternal revenge on Dellwo, intensifies feverishly. New colleague Jan Gröner tries to take Dellwo out of the competition but keeps missing him. The head of the homicide squad, Fromm, and public prosecutor Scheer discuss with the marathon organizers whether there is a possibility of canceling the competition. Criminal assistant Ina Springstub determines all the churches along the route, which are then stormed by SEK officers. Only Inspector Singer seems to keep calm in the hustle and bustle. She intuitively follows her own trail. The clock is ticking - and a race against time begins...