Turner and Perkins find themselves in awkward position when one of the suspects arrested in a raid on a counterfeit car parts business turns out to be none other than an undercover Masters, who has been working undercover for a haulage firm involved in gun-running alongside her long-time informant, Seth Mercer. Although initially reluctant to co-operate, Masters eventually agrees to let her former Sun Hill colleagues provide back-up for a planned meet between rival dealers Dougie Clark and Phillip Hanson, but the deal goes badly wrong when Hanson recognises Mercer from his days as a supergrass. Meanwhile, Harman and Kapoor break-up a fight between relatives at a funeral.