Thirteen-year-old Sully Stringfellow, his arch-nemesis Izzy Cisco, friend Moleman, and a league of long-forgotten plumber heroes team up to save Nitro City from mutant creatures in the sewers.

"It was supposed to just be a normal basement--some storage boxes, dust, you know, the usual basement stuff. But when Milo is sent by his mother to fetch a sock from the basement of the historic home they've moved into, Milo finds a door in the back that he's never seen before. Turns out that the basement of his house is enormous. In fact, there is a whole world down there. As Milo travels ever deeper into the Basement World, he meets the many Things...

"When Hyacinth Hayward tries to learn more about the magical rivers under London and how her family is connected to them, she stumbles upon a plot to steal the ancient stones that hold the city together"--

"Behind a hole in their basement wall, Chirri and Chirra discover a network of tunnels. Join them as they visit moles, discover caves full of glowing flowers, poke at the roots of growing plants, traverse a subterranean lake, and spend the night with a family of badgers!" --