Plastic surgeon Martin Sobotka was poisoned in his Buchum villa. His safe is empty, his last caller and Internet date Michaela Weber claims Sobotka handed her his precious coins collections to estimate and catalog to be exposed indefinitely in a museum. Given her husband's suspicious end -no court case however- Heldt suspects a 'black widow' and convinces commissioner Grun to postpone his wedding anniversary to play the perfect prey under alias Herr van Verde. Flirting with a uniformed cop makes Heldt ruin a precious prop and sneaking off to illegally search her home allows repeating the venomous trick, but it's not sufficient to prove murder. Martin's maid pawned a stolen coin and fails to hide her saucy alibi. Grün suspects dissatisfied patients, some of whom sued Sobotka.