Ben is stuck. His parents' divorce left him trapped in a backwater town, and he's just been caught breaking into a fairly big corporation's servers and they're going to try him as an adult.Essa is also stuck. A vengeful ex-lover left her trapped in a backwater world, and she has no way back home to the Well, the vast bottomless pit lined with doors to countless realities.A lucky accident (not so lucky for Ben) frees Essa and now they're both in the Well, with its invisible lizards, cities hung from cats'-cradles and Library made of sand.Essa wants revenge. Ben wants a way home. The awakening of an ancient threat to the Well puts both their plans on hold. On the run, their only allies a clockwork spider and a girl made of iron, they'll have to work together to save all the worlds.