(From the publisher):
When "Radish" Rademacher discovers a mysterious cave filled with an odd treasure, he joins forces with his twin sister Steffi and her friends, Collin and Norbert, who have formed their own detective agency: Collin and Co. Unfortunately, Collin and Norbert have their reservations about letting Radish join the gang. Is the treasure he found real? And if so, does Radish have what it takes to be a true detective?
Original title: 4 1/2 Freunde
Genre: Fiction→ Children & Young Adult→ Mystery