The series is named after a small part of Saltsjöbaden called Solsidan. It revolves around Alex and Anna who are expecting their first child and have just moved to Alex's childhood home in Saltsjöbaden, Stockholm County. Alex tries to get Anna to enjoy herself, and at the same time spend time with his childhood friend Fredde.

A hereditary and supernatural illness slowly twists the relationship between a boy and his mother. Through the course of 20 years Simon comes to learn of this illness and finds out that his mother will one day be consumed by it. When the time comes that the mother can no longer take care of herself, Simon is put to the test.