A chilling phone call during Astrid's radio show stirs up memories about her sister's disappearance and spurs her to investigate what really happened.

Astrid returns to her childhood home to look for clues. Ida's relationship with Jakob unfolds and his fascination with a mysterious book takes root.

Jakob leads Ida, Amelia and Falke to the island for the equinox. After learning more about the strange symbol, Astrid questions a former teacher.

The pieces begin to fall into place for Astrid with help from Ida's old friend, but the visions that plagued her as a child shake her hold on reality.

A return address yields more clues, but Astrid's relentless search for answers causes concern. Ida feels lost and alone after the events on the island.

Astrid confronts her mother as she closes in on the truth. Anger, accusations and revelations mar Ida's long-awaited graduation day.