Yeah another poster had all the info that the story itself lacks.

"After reading the pilot I can tell you it's about a detective whose fractured psyche creates two alternate realities for himself in his sleep (hence the title REM). In one reality his son is dead, and the other his wife murdered. But in reality he's lost them both. It's very 'Inception'-esque and well written. Should be good. Just hope audiences can follow it."