When a teenage school girl is killed Connor and the others struggle to find the killer. When an American profiler sees the connection between the girl's death and previous unsolved murders the team realises that a serial killer is on the loose.
As the killings continue Connor and the team struggle to find the culprit. Connor finds herself more and more reliant on Max.
When a school teacher is found dead her boyfriend is arrested when he is found covered in blood but he is unable to remember anything about what happened. Walker is not as sure as the rest of the team that he is guilty.
It becomes obvious to the team that serial killer is on the lose when more victims die in similar circumstances. The team are desperate for Milton to remember more events from the night his girlfriend was murdered to help with the investigation.
When a mother returns home she finds her child dead and her nanny gone. Connor and Walker find out that the nanny has a criminal past and try to find her before she commits another crime.
The team continue to try and find the dead baby's nanny. As the investigation continues a revelation leaves them with an unexpected challenge.
When a police commander and his magistrate wife are found murdered, Walker and team investigate. What makes it worse for Walker is that they are friends of his.
Walker tries to find proof that the Delany brothers' are lying despite CCTV footage backing up their alibi. When the murder weapon is found the team believe that it could help lead them to the murderer.
An ambulance is forced off the road as it is carrying a famous patient in the back. The patient is then shot in the head.
Imogen's mother makes a plea for her daughter's safe return. Things happening between McGill and Connor threaten the investigation.
An accident happens at a fair when a girl falls to her death from a ferris wheel. DS Satchell's aunt who is a fortune teller believes that foul play has happened though. When a second death happens at the fair it looks as if she could be correct.
Pavel is arrested but when some new evidence is found it pushes the investigation in another direction.
A family known for their involvement in crime are involved in a robbery at a jewelers where the manager is murdered. One of their accomplices becomes an informer and is also killed. DS Satchell finds his life and his young daughter's life in danger when he witnesses the latest killing.
DS Satchell is desperate to find his wife and daughter now that they are misssing. Walker and Connor try to find the evidence to put the Bilkin family behind bars. Satchell decides to take matters into his own hands when he feels he has nowhere else to turn.