When 10-year-old, sassy, enthusiastic detective Roxy Sauerteig, driven by an irrepressible love of investigation, moves to Berlin with her mother, she plops right into the biggest case of her life involving a museum theft worth millions. But Roxy, who has grown accustomed to being a lateral thinker and a loner who gets in trouble everywhere, can only solve this case with the help and friendship of two other loners: the snarky Annaté, daughter of the museum director, who is suffering from her parents' divorce, and the quirky, mysterious "everything collector" Mr. Grindelmann.