At the Incirlik Air Base in Turkey, a lieutenant called Hatice reports unusual solar waves.

They become aware of a global catastrophe: the Sun has become lethal to humans without thick shielding such as deep water.

They arrive at Kos where a military submarine, the Yakamoz S-245, has surfaced, and the two crews join forces.

After further events they decide to head for a seed vault in Norway, tying the program into its sister series Into the Night.

[3] Shooting took place in various locations in Turkey: İzmir, Balıkesir, Foça, and Ayvalık (especially Cunda Island)[4][5] as well as on a Turkish Atılay class submarine.