In the overcrowded world and cramped space colonies of the late 21st century, tedium can be endured through the use of the drug Can-D, which enables the user to inhabit a shared illusory world.

When industrialist Palmer Eldritch returns from an interstellar trip, he brings with him a new drug, Chew-Z, which is far more potent than Can-D, but threatens to plunge the world into a permanent state of drugged illusion controlled by the mysterious Eldritch.
The Three Stigmata of Palmer Eldritch is, by universal consent, one of his three key novels, and the book in which he first took his perennial interest in the fragile nature of reality to a new level of imaginative intensity.