When an autistic teenager is discovered wandering lost at the side of the road, DS MJ Croft assumes he is a missing person. However, she soon realises that it is the boy's mother who has disappeared, and becomes worried for her safety. Meanwhile, DC Jason Doyle and Amy Garnett deal with a young woman whose fiancé has disappeared suspiciously.

When a 16-year-old girl goes missing, her parents claim it is completely out of character, and are distraught when DS MJ Croft, head of the Dover Missing Persons Unit, finds vodka in the teenager's bedroom. DC Jason Doyle, however, is suspicious that the father is abusing his daughter. Meanwhile, Amy helps 65-year-old Stan Marsh search for his long-lost twin brother.

The team investigates when Tom Laird's wife Irene vanishes suddenly, and DS MJ Croft comes to blows with her superior, DCI Ford, when she suspects Tom of murder. MJ is not convinced when new evidence reveals another side to Irene. Meanwhile, Amy is keen to find Martin Cadzo, who disappeared after testifying against his father in a fraud trial, and whose uncle has left him a large inheritance.

The father of a little girl goes missing, and DS Croft suspects that the younger brother is involved. As they dig deeper, they discover that a shocking secret has caused Paul Garrison to flee his family.

DS MJ Croft and DC Jason Doyle suspect money problems when a pregnant woman reports her boyfriend missing, and Amy's investigations into the case put her in danger when a witness turns nasty. Meanwhile MJ is getting closer to her missing sister.

When a six-year-old child goes missing from school, DS MJ Croft and her team at the Dover Missing Persons Unit are under pressure to get results. Her parents are distraught when CCTV footage shows her getting into a car, and MJ is forced to bring CID into the investigation. Outside work there is a surprise for MJ when her estranged father Jack suddenly reappears in her life.