The unscripted crime drama following the work of a group of detectives returns. DS Charlie Steele must keep DS Jack Weston under control as they investigate the murder of a detective inspector, who has been shot dead in her bed. DCI Daniel Drummond heads the investigation, bringing in DS Alisha Brooks and DC Gary Roscoe from Major Crimes to help, but there is shock in store when it turns out one of the detectives knows more about the murder than they are letting on.

Using improvised dialogue and filming techniques usually associated with factual programming, this unique procedural crime drama follows D.I. Martha Bellamy and her team as they investigate hard-hitting crimes in contemporary London.