Plot summary

Cube Route contains a crossover

Fictional crossover

A fictional crossover is the placement of two or more otherwise discrete fictional characters, settings, or universes into the context of a single story. They can arise from legal agreements between the relevant copyright holders, or because of unauthorized efforts by fans, or even amid common...

 to Phaze, a world in Anthony's seven-book Apprentice Adept

Apprentice Adept

Apprentice Adept is a seven-book fantasy and science fiction novel series by Piers Anthony. The series takes place on Phaze and Proton, two worlds occupying the same space in two different dimensional planes. Phaze is a lush planet of magic, where Proton is a barren mining planet of science...

series.

Summary

In the magical land of Xanth, wishes are far more than mere words. So when a Plain Jane called Cube whispers a wistful wish to be beautiful, she finds herself leading a company of colorful companions on a search for the mysterious Cube Route--a perilous path that leads to danger, adventure, and perhaps her heart's desire as well.

This curious quest takes them all over Xanth, into the mythical realm of Phaze, and even to our own world, where Cube rescues a beautiful human woman from a very ugly situation, ending at last in a mysterious Counter-Xanth where things can be transformed into their opposites in the wink of an eye.

End of the first trilogy

The title and theme of this novel plays upon the common joke that Anthony had originally intended only a trilogy of novels, but as they kept appearing, kept calling it an "extended trilogy." This book concludes the "first trilogy" as it is twenty-seventh (three cubed) novel. He has now started on his "second trilogy."