12-year-old Conni is a curious, adventurous girl with a strong sense of justice. With her best friend Paul in tow, she loves to explore the world and to discover new things. When her old school closes, Conni has to enroll in the school of strict principal Möller. Hoping to make a fortune, mean-spirited Möller wants to turn his little pup Frodo into the star of a dog food commercial. In their attempt to free Frodo from Möller's clutches, Conni and her friends can also rely on Conni's clever Grandma Marianne.