Ben and Michaela investigate a shocking murder in fear that it's connected to Flight 828. Meanwhile, Ben struggles to accept the life Grace led in his absence, while Olive and Cal realize that being twins after five and a half years apart is harder than they thought.

Ben forms an unlikely partnership with Vance in a high-stakes race to locate the missing passengers of Flight 828. Meanwhile, Michaela helps a suicidal passenger who believes he is the Angel of Death, and Cal goes back to school, navigating both his unwanted celebrity and his former friends, who are all now 16 years old.

When Cal is discovered missing from his bedroom, Grace and Ben launch a desperate search which takes them to the remote mountains of upstate New York. A tantalizing trail of breadcrumbs leads them to a startling, game-changing discovery. Meanwhile, Michaela confronts the deceptive Autumn, and the shadowy "Major" finally makes an appearance.

Another non-passenger appears to have come back from the dead, and Ben, Michaela and Saanvi want to know why now and why him. This mystery-man is also having callings. Saanvi experiences PTSD.