When astronaut Spencer Armacost returns to Earth after a mission that nearly cost him his entire life , in order to see his wife, Jillian, more frequently he decides to have a desk job. Jillian finds that Spencer's personality appears to get shifted, but her concerns fade when she discovers that she's pregnant. Since Jillian grows nearer to becoming a mommy, her suspicions about Spencer yield. Why does this seem as if he's a different person?