This is one of Philip K Dick's earliest novels (his ninth, in fact), originally published in 1955. As such, it makes for compelling fiction with a science fiction-like twist, but may not be classified strictly as "science fiction". It takes place in the then near-future year of 1957, when eight people are involved in a tragic lab accident that transports them through time and space to a multitude of various worlds and states of consciousness.
The worlds are eventually revealed to be solipsistic manifestations of the inner worlds of some of the book's main characters. Each one embodies the secretly-held thoughts of its creator, trapping the group inside a unique universe with its own set of ethics, rules, and scientific principles. The central protagonist, Jack Hamilton, figures out what is going on and helps the group travel through each world—by the skin of their teeth, mind you.
Although I wouldn't advise a PKD novice to read this as their first book of his to check out, it is a solid novel. The characters are well-fleshed out, the plot is fairly engaging, and the writing makes for a quick and easy read. I am very glad to have finished this one, and I doubt I will return anytime soon. But maybe I will.
3/5 stars. 243 pages.