Ulla, a teacher from Roskilde, has celebrated her 30th birthday with a big party among friends and relatives. On her way home from the party she disappears without a trace. Her husband calls the police and Unit One is summoned. Evidence indicates that a crime has taken place, and Ulla's children also face danger. Ingrid is in an awful state following Søren's death and has incarcerated herself. Gaby and Johnny try to help, but in vain. However, IP has his own way of tackling Ingrid. Fischer receives a tempting offer from Ulf.