Tapper Watson is just an ordinary Erisean boy who loves adventure stories. But when one of his sixty-seven cousins sends him away on a smugglers' submarine through the River Lethe to other worlds, he just wants to go home again. On an unscheduled visit to Earth he meets Fern Shakespeare, and a talking plant called Morse, and their adventures begin. And when he finds himself being chased through worlds by a pair of trigger-happy lobster mobsters in search of the mysterious Nemo Machine, Tapper begins to realise that he might not be so ordinary after all.