On the first day of Yom Kippur, the commanding officers at a top-secret Israeli military facility fail to heed the desperate warnings of Avinoam, a young intelligence analyst convinced that a war is about to break out.

Yoav leads his small unit in an against-all-odds fight to protect the Hermon intelligence soldiers. Dafna resists orders for all women to evacuate the front lines and the 87th is thrust into battle and suffers a devastating loss.

After Syrian forces infiltrate Hermon, Avinoam attempts to lead his fellow soldiers to safety through the facility's secret tunnels. The 87th grows increasingly worried about the mental stability of their new commander, Caspi.

Beyond hope of rescue and with no way of returning to safety, Marco leads the 87th in a rebellion to subdue Caspi, and Avinoam makes an unlikely connection with a Syrian soldier.

Marco tries to use a stranded pilot as leverage for a rescue mission. Melakhi remains determined to find his friends, and Avinoam and Yoav find a common bond in the most dangerous of circumstances.

Meni challenges the army's seeming indifference to his son's fate. Dafna takes on a mission no one else is willing to handle, and Avinoam does his best to bring a wounded and desperate Yoav to safety.