The series tells a story of Polina Klochko, a schoolteacher of English, whose life changes drastically after her little son Mark is kidnapped from the kindergarten. A few years later, Polina sees her son in a newscast about an incident in a Riga shopping mall.
She goes to the police asking to resume the investigation, but she lacks grounds for it.
Polina decides to return her son herself and eventually meets an ex-police major Denis Denisov, who is also a father of one of her students. Helping Polina to find her son, the experienced cop notices too many strange coincidences in similar cases for the recent five years.