Book 1

Lilith

by Jack L. Chalker

Published 12 September 1981

Book 2

Cerberus

by Jack L. Chalker

Published 12 December 1981

Book 3

Charon

by Jack L. Chalker

Published 25 April 1991

Book 4

Medusa

by Jack L. Chalker

Published 12 March 1983