In an attempt to end the standoff on Sainte Marina, Marcus and Sam enter into tense negotiations with the U.S. Government. Meanwhile, when a critical system fails, Grace must take command of the Colorado on a perilous repair operation.

As Marcus and Sam hunt for the traitor in their ranks who stole their nuclear launch key, Prosser disobeys orders and starts a small war he can't control. Meanwhile Grace and James must work together to defuse a dangerous situation, as back in D.C. Christine is indicted as Sam's co-conspirator.