THE FIRST PHONE CALL SHOCKS A FAMILY.

Kolbeinn has been called to his old home. The new owners uncovered some photos, and a muddied child's shoe bearing the name 'Salvor'. A name Kolbeinn doesn't recognise. Soon after, he hears news of his mother's deteriorating health. Her carers say she has been asking for her daughter, his sister: Salvor.

THE SECOND TRACKS TWO MISSING COUPLES.

Jóhanna is working with the search and rescue team in Höfn to find two couples from Reykjavik. Their phones' last location has been pinpointed to the road leading up into the highlands. In a harsh winter, the journey is treacherous, and they soon find the first body. More troubling, Johanna senses her team is being tracked through the snow.

A THIRD FROM BEYOND THE GRAVE?

Hjörvar works at the Stokksnes Radar Station in the highlands. He's alone when the phone connected to the gate rings: the first time it's done so since he began working there five months ago. When he answeres, he can only hear interference, and what sounds like a child's voice asking for her mother.

How are these events connected?

And what may be searching for its prey out on the ice?