“400 Days” centers on four astronauts sent on a simulated mission to a distant planet to test the psychological effects of deep space travel. Locked away for 400 days, the crew’s mental state begins to deteriorate when they lose all communication with the outside world. Forced to exit the ship, they discover that this mission may not have been a simulation after all. Four astronauts training for deep-space travel gradually become unhinged when strange things happen and they sense the test run may actually be real. Something sinister is tearing them apart. Then, everything they thought they knew is not at all what it seems.