Sleeping, eating, hunting annoying robin Ralf, sleeping. Tomcat Knutbert is living his best life – until one day, said life is gravely disturbed. A beast is wreaking havoc in his neighbourhood and because Knutbert happened to be one too many times in the wrong place at the wrong time, he becomes suspect number one. To wash himself clean of all accusations and save his fur, he has to get matters into his own paws and catch the real culprit – with unexpected consequences. Suddenly, Knutbert finds himself with a pet rat on his paws …