University ice-sailing trainees face a hostel fire when caretaker Krenzel rescues Captain Klaus’s swapped suitcase, barring him from travel due to a stolen Hogarth print inside. X-rays reveal a hidden engraving; detectives Hübner and Lindt expose forger Sander and Krenzel. After Krenzel’s sabotage fails and both are arrested, Klaus is exonerated and rejoins his team for the international regatta.