Solaris

Prot is a patient at a mental hospital who claims to be from a far away Planet. His psychiatrist tries to help him only to begin to doubt his own explanations.

K-PAX features psychological, odd, atmospheric, touching and surprise ending style.

In Lem's novel, character Rheya is named Harey, an anagram of Rheya. This is probably a reference to the titan "Rhea", who was mother of the Gods in Greek mythology, and which is also the name of a moon of Saturn. Rhea was the wife of Cronus/Saturn (the ruler of time), and the sister of Oceanus (Solaris is an ocean planet) and Tethys, a sea goddess, as well as the mother of Poseidon/Neptune; her parents were Uranus (the sky god) and Gaia (the earth goddess).