Shot in the style of a fly on-the-wall documentary, Suspects is unscripted, with the cast devising their own dialogue based on a detailed plot description. Set in London, each episode is a self-contained story, starting with a news report, then following the team of three detectives as they investigate the circumstances the crime. The cases themselves are hard-hitting with contemporary themes, such as the search for a soldier with PTSD, a murder that has been made to look like an assisted suicide and the gang rape of a young teenager. Each detective has their own distinctive style of working. The team leader, DI Martha Bellamy, maintains an overview but also sits in and conducts the questioning of suspects. Her team know that she is behind the mall the way and will fiercely defend them when necessary.