The 4 ½ friends consist of three boys, one girl, and a dog. Kale, the founder and leader of the detective agency "Kale and Co.," the twin brothers Steffi and Karsten, Friedel, and their dog, the Handsome One, get involved in various adventures as they try to solve mysteries and strange cases.

The Handsome One, the dog of the 4 ½ friends, is upset. His friends want him to star in an advertisement, but his dignity does not allow it. Moreover, he cannot stand his co-star in the ad, the arrogant Fluffy, who has a perpetual cold and a diamond collar.

However, some have set their sights on this precious collar, and on the first day of filming, Fluffy falls victim to a kidnapping. The Handsome One, thanks to his excellent sense of smell, immediately picks up the first clue and a new adventure begins for the 4 ½ friends...