When Cal wakes with a life-threatening fever, Grace worries it's a side-effect of his experimental cancer treatment, but Michaela and Ben suspect Cal's condition may be related to a mysterious passenger from Flight 828. As Cal's situation worsens, Ben and Michaela attempt to track down the now-missing passenger.

While investigating a Calling, Michaela finds a mysterious stowaway. Ben clings tightly to his beliefs. Cal comes out of hiding to pursue a lead.

Hidden voices on the black box draw Saanvi in. Cal sneaks to see an apprehended Henry. During a podcast appearance, Ben seeks help.

Everyone is forced to adjust as Cal guards a secret, Eagan pursues his own mission, and Michaela uncovers a tragic murder.