Parts of a body are found in a scrapyard. Meanwhile, after making the decision to retire from the police force, Cassie faces a dilemma when she learns she isn’t entitled to her full pension payment unless she completes her 30 years of service.
Cassie and Sunny identify four potential suspects who trained as police officers together, and two of them are still serving. They have no luck finding the rest of the body and decide to go public about the discovery of Walsh’s remains.
Cassie and Sunny interview the four suspects, who all deny knowing the victim. Boulting discovers Walsh was cautioned three weeks before his death, and Collier manages to locate the rest of Walsh’s body.
Cassie and Sunny discover Walsh was chased by all four suspects on the night in question. Willets realizes Fiona’s blood sample may have been deliberately lost by Liz. The pathologist identifies a cause of death implying Walsh was murdered.
Cassie and Sunny interview two of the suspects again and get closer to the truth of what happened to Walsh. Balcombe believes she may have found the cause of death. Unexpectedly, things take a devastating turn for Cassie.
Despite a tragic turn of events, the team narrows down the suspects. Will they find conclusive proof of who the murder weapon belonged to and succeed in bringing Walsh’s killer to justice?