Class teacher Mr Slink sets an environmental project assignment, and Halo Nightly pairs up with Flora, the school's resident treehugger. Their team has the assignment in the bag (reusable, of course). But when the evil Doozie Hiss ruins their chances of getting a good mark, Flora changes from happy hippie to eco-terror. With her superpowered sweets, Halo faces off against the Green Queen of Mean! Part of the Princess Candy series.