Alison Woods, a deaf woman with lip-reading skills, is enlisted by the police to lip read the conversations of a criminal gang planning a dangerous heist. She works closely with the police to gather intelligence by watching live feeds and trying to catch the gang's plans, despite some police officers advising her to stick strictly to lip reading and not get involved in the investigation itself.

The main criminal characters introduced include gang members named Hulk, Cruella, Wolf, and Liam. Cruella's husband is mentioned as being in Belmarsh prison for 10 years for manslaughter related to a previous armed robbery, which adds tension to the story.

Alison faces challenges such as limited access to the gang's conversations, needing to be physically closer to lip read effectively, and police officers cautioning her to avoid researching the case or getting too involved. Additionally, she struggles with the emotional complexity of the case, especially as she begins to care for one of the suspects, complicating her role.

The police investigation is portrayed as tense and methodical, focusing on surveillance and intelligence gathering. DS Ashleigh Francis leads the case and brings Alison in for her unique lip-reading skills. The investigation involves monitoring live feeds, tracking gang movements, and dealing with internal frustrations, such as James blaming himself for past events related to the gang.

Episode 1 establishes a tense and dark tone, with themes of crime, loyalty, and the personal struggles of those involved. The show highlights the mental games between police and criminals, the challenges faced by a deaf informant, and the emotional stakes of the investigation. There is also the presence of strong language and some rough treatment of characters, contributing to the mature and serious atmosphere.