A staff change at Mission Control upsets the usually unflappable Lu, and the fallout undermines Emma's command. Matt encourages Lex to return to school.

Emma puts herself in harm's way when Ram unwittingly endangers the lives of everyone on the Atlas. Matt must make a wrenching decision about his future.

As Christmas approaches, the crew prepares to make their final calls home before communication grows spotty. Matt and Lex adjust to their new normal.