Rupert Venables is the junior Magid assigned to Earth, and to the troublesome planets of the Koyrfonic Empire as well. The Empire is situated right at the twist at the center of the Multiverse. There is a problem of succession when the Emperor dies without a known heir, paralleled by a more personal problem on Earth when Rupert's senior dies, and appoints him senior. Now Rupert must search the Earth for an appropriate new Magid, while helping part-time to prevent the descent of the Empire into chaos.

And then the problems become intertwined when Rupert finds that he can meet all five of the potential Magids on Earth by attending one SF convention in England. And that other forces, some of them completely out of control, are there too.