As the mission launches, Emma finds her mettle as commander tested by an onboard accident, a divided crew and a family emergency back on Earth.

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.

A problem with Atlas' supply ship jeopardizes the mission and sparks questions about Emma's commitment to landing on Mars.

Emotions run high as rapidly dwindling water rations on the Atlas leave the crew and Mission Control scrambling to find a fix before time runs out.