School's out for the summer! Leo has decided to spend his summer mowing lawns to make some cash. One of his customers is an eerie lady who tells him his daily fortune and is very into astrology. Meanwhile, Tia discovers a strange creature in the sewers while doing some volunteer work. Could Leo and Tia's summer mysteries be connected? And what will they do when faced with magical mind control and forces from out of this world? It's never a dull moment for the Lunch club, and the sixth volume of Dom Pelletier's hilarious graphic novel series is no exception!

Translation of: Le mystère du marais.