Arman reluctantly embarks on a submarine research trip sponsored by his father. At the Incirlik Air Base, Hatice reports an unusual radiometer reading.

Inside the submarine, tensions come to a head between Arman and Umut. When Barış's actions unravel, Erenay confronts an impossible dilemma.

Amid a search for survivors in Kos, Arman and Defne rush to find Kenan before sunrise. Felix and Cem scramble to restore electric power to the town.

Umut reads a message from NATO that leads him to lash out against Arman. Arman sets a trap for Umut and speaks to his father on the phone.

Arman and Yonca must swim out to fix a rupture, but the submarine is still in jeopardy. The Yakamoz crew discovers an intruder.

After Hatice reveals a shocking truth about Erenay, Umut and Yonce begin to suspect Defne. The crew tracks an airplane. Cem makes a devastating choice.

Umut decides to switch course and head for a seed vault in Norway. Hatice snoops inside Defne's room. The crew docks in Spain, and carnage ensues.