Amelia has recently had a cochlear implant fitted and is undergoing intensive speech therapy – and learning to hear for the first time. Joining in with the chaotic and lively household, Amelia volunteers to take the dog for a walk, and witnesses the audacious murder of a policewoman. Reluctantly she is propelled into a loud and frightening world.

Amelia identifies one of Jane Shilliday's killers, a detective on the Drugs Squad. When Jim learns that Rocky and Shilliday were romantically involved, he is certain that the large scale corruption on the Drugs Squad was the motive for Jane Shilliday's murder, but he can't prove it. When Amelia's implant is returned to her via her audiologist, she realises, with horror, that Shilliday's killers know who she is.

Amelia and Jim's families are subjected to intimidation tactics by the corrupt Drugs Squad in an attempt to thwart the investigation into Jane Shilliday's murder. When Amelia lip reads a conversation between Rocky and Mac and relays the information to Jim, he becomes certain that Mac is Jane Shilliday's other killer. When Lee Griggson comes to Amelia's house to intimidate her, she runs away, without taking her cochlear implant.

In an explosive finale, Amelia heads to a rural police station, but refuses to reveal her identity, worried that the corrupt officers on the Drugs Squad might be able to track her down. Amelia believes her location has been breached and makes contact with Jim, who races to collect her. He realises too late that Mac and Lee have followed him and confronts them, insisting Amelia head home for her own safety. Amelia tracks down Rocky at the boxing gym and in a big showdown reveals that Mac and Lee murdered his girlfriend. Rocky decides to come clean about the Drug Squad's corruption to obtain a justice of sorts for Jane Shilliday's murder.