In the original five stories, psychologist Harold Shea and his colleagues Reed Chalmers, Walter Bayard, and Vaclav Polacek (Votsy) travel to various parallel worlds where ancient myths or old literature are reality.

In the course of their travels, other characters are added to the main cast, notably Belphebe and Florimel, who become the wives of Shea and Chalmers, respectively, and Pete Brodsky, a policeman who is accidentally swept up into the chaos.

A final planned story set in the world of Persian mythology was never written, nor was a projected response to L. Ron Hubbard's misuse of their hero in his novella The Case of the Friendly Corpse (1941).

His interest appears to have shifted to debunking the less credible aspects of the universes visited, rather than taking these as a given and extrapolating the fantasy worlds' physical or magical laws from them, as in the previous sequence.

On the other hand, some of the new authors made efforts to duplicate de Camp and Pratt's original achievement, exploring fresh venues where their heroes once again have to learn the world's fundamental magical rules from the ground up.

Holly Lisle ("Knight and the Enemy"), John Maddox Roberts ("Arms and the Enchanter") and Tom Wham ("Harold Sheakespeare") were among the authors who recreated the original formula.

The initial impulse for the continuation may have been the successful adaptation of the characters into Tom Wham's authorized gamebook adventure Prospero's Isle, published by Tor Books in October 1987 (the basis of "Harold Sheakespeare"), to which de Camp had contributed an admiring introduction.

This may have encouraged him to wrap up long-unresolved loose ends from the original series, such as the stranding of Walter Bayard in the world of Irish mythology, and to resolve the unaddressed complication introduced by L. Ron Hubbard's "borrowing" of Harold Shea for use in his novel The Case of the Friendly Corpse.

Once the loose ends are resolved, most of the action in the second sequence involves Shea and Chalmers' quest across several universes to rescue Florimel, who has been kidnapped by the malevolent enchanter Malambroso.