Watch State of Play Season 1 Online

Teenager Kelvin Stagg is shot dead in a London street. Then politician Stephen Collins breaks down when he hears his assistant Sonia Baker has been killed by falling under a train. A newspaper editor asks his journalist Cal McCaffrey (Stephen's former campaign manager) to look for a connection between the two deaths, and McCaffrey finds the dead teenager had stolen a silver metallic briefcase. McCaffrey traces the briefcase and in it he finds pictures of Stephen and Sonia - and a gun.