When Penny and her detective gang learn about the first missing Christmas trees, they think it is just a coincidence. Soon, however, things become clear: it is the work of a serial offender. An entire tree plantation burns down, another is afflicted by a rare disease, orders disappear, and someone steals the last fir trees from balconies. For Penny and Co., this is unheard of. Christmas without a tree is like... well, it's just not Christmas. The girls are patient and soon stumble upon a hot lead...