When a student's school reports a girl missing, the squad must track down a trusted family friend for answers; Benson gets a Mother's Day surprise.
Abe and Harper's investigation into a marine recruiter's alleged misconduct derails when the key witness refuses to testify.
Harper gets caught in a firefight when she, Abe and Maya travel to Syria to investigate a Marine accused of desertion; Colonel Turnbull travels to Germany to be with her wounded son.
When a Marine is accused of helping a terrorist escape from Guantanamo Bay, Abe and Harper believe that they have an open-and-shut case, until they are mysteriously denied access to key evidence without explanation.