Series Twelve is one of the Related Worlds. It contains the worlds Twelve-A, the world where most of the books take place, and Twelve-B (our world) where Janet Chant comes from. Twelve-A has inhabitants that use magic (which is divided into many types), while Twelve-B does not as it split off and turned to science and machinery. Also, in Twelve-A there is a continent across the Atlantic called Atlantis, the greatest magical achievement was the Wars of the Roses and in the Battle of Agincourt was won by the French rather than the English since Richard the Second was on the throne until after the events of the Battle of Agincourt. Twelve-B appears in The Lives of Christopher Chant. In Twelve-A, the king of England is called Charles the Seventh.

The Related Worlds
Series One, Series Two, Series Three, Series Four, Series Five, Series Six, Series Seven, Series Eight, Series Nine, Series Ten, Series Eleven, Series Twelve