Return To Sender (A Dead Letter At The Speed Of Light) (1985, by Perry Hoberman and Bill Obrecht) is a science fiction play for four live actors lipsyching to the pre-recorded voices of four other actors. Stereoscopic 3D projections are used to create various environments, both real and imagined. A technical crew of the future, hurtling through space on a routine mission to an interplanetary resort, gets rerouted to an unknown destination (because they know too much - of course). On their way there, they pass the time in artificial environments, electronically induced hallucinations which are generated by devices known as "multi-encephalic reactors" or "blenders". But these supposedly fictional experiences begin to be interrupted by hidden messages, indecipherable signs, cryptic warnings of doom.