In Episode 5, Rose follows a lead related to Sam Haig's death at a climbing wall centre, where she and Carl question a man who found Sam's body and a pregnant woman who disapproves of Sam's relationship with Paul, revealing tensions around Sam's social circle and the circumstances of his fall.

The disappearance of Merritt Lingard is linked to Sam Haig's death because Merritt went missing the day after Sam died, and they were in a relationship. This connection prompts Carl and Akram to investigate the circumstances surrounding both events closely.

Carl struggles with the pressure of running Department Q and handling the Merritt Lingard case, including delivering a public statement that causes him a panic attack. He also faces skepticism from colleagues and interference from Moira, who assigned him the cold case squad possibly to have him work alone and clean up past mistakes.

Episode 5 reveals a potential financial motive behind Merritt Lingard's disappearance, with DI Hardy uncovering signs of institutional corruption. Carl confronts Moira about her decisions and the initial investigation, suggesting that corruption and cover-ups may be obstructing the case.

Key characters include Carl Morck, the lead detective; Akram, his assistant who selects the Merritt Lingard case; Rose, who follows leads on Sam Haig; Moira, who oversees Department Q and pressures Carl; Merritt Lingard, the missing prosecutor; Sam Haig, whose death is connected to Merritt; Paul and Chloe, individuals connected to Sam's social circle; and Dr. Fiona Wallace, who refuses access to William, Merritt's disabled brother.