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 increasingly worried for her safety. DC Jason Doyle and Amy Garnett deal with Jan, a young woman whose fiance has disappeared in what seem like suspiciously fraudulent circumstances. And MJ is shocked when her friend, radio DJ Danny, asks her on air about her sister, Ellen, who went missing over ten years ago.
When a sixteen-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. Meanwhile, Amy struggles to connect with a woman claiming to be searching for her missing father, and her investigation reveals that the woman has been lying and is in fact missing herself. MJ gets disturbing news about her missing sister, Ellen.
In the concluding part of the drama, 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 real danger when a witness turns nasty. Meanwhile MJ is getting closer to her missing sister Ellen, but she may not get the happy ending she was hoping for.