Ubik

Arguable PKD's most iconic work, and definitely one of his strangest. In a far future humans are colonising the Moon and developing strong psychic abilities. Companies are employing psychics to sit in a room and do industrial espionage from a distance. One company sends a team of them to the Moon for such purpose but there is an explosion and not everyone survives.

Second story strand: People who are almost dead can be put into cryo-sleep and kept alive. They can be temporarily brought out of sleep for conversations through a psychic medium. But these sessions shorten the ultimate storage time possible for the person.

Put these two strands together. Some of those sent to the moon have died and are in cryo-sleep.

Everyone tries to get on with their lives, but strange things keep happening. It seems time is running backwards and everything is inexplicably old. And then Ubik appears in advertising. It's the universal fixit. One spray and everything is good again. But what is in the can and where do you get it?

PKD puts together a narrative that has the reader questioning 'who is alive and who is in cryo-sleep?' And does it even matter? After all, PKD's ability to blend the reality of human consciousness with weird alternatives is never ending.