Hari has spent his whole life faithfully 'running the Wheel' for his colony, generating power for the Light to help outsiders find their way back home. It is the only life he has known, safe and secure under the protection of the Guardians. Only - nobody has even seen any outsider return. When strange events begin to occur which the Guardians seem to cover up, Hari begins to question the life he is leading, and soon finds himself on an unfamiliar journey with his partner Heti to uncover the truth - and a great danger which will threaten the lives of everyone he knows and loves.