4. Unsafe

When a treasure hunter with a metal detector uncovers a nine-year-old skeleton in a shallow grave aside the Thames mudflats, it forces Brooks and Devlin to reopen a contentious murder case when they identify the remains as those of David Ackroyd who disappeared in 1999. His supposed killer and business partner, Luke Slade ( Iain Glen ), was eventually convicted of murder although no corpse was found and an unreliable witness claimed that Slade told him he had slit his victim's throat but the medical examiner finds that he was shot in the head.

As a result, it would appear that Slade is the victim of a miscarriage of justice. Steel, however, is far from convinced and, when Slade represents himself in court, it becomes less about the trial and more about the vendetta between the two men. Slade soon files a writ to have his conviction overturned and the Crown prosecutors learn that Slade will represent himself at the appeal. Whilst in jail Slade has become skilled in the law and wins himself a re-trial, putting James Steel's career on the line in the process as was the original trial prosecutor as this was his first case with the Crown Prosecution Service.

Steel and the police have to build an entirely new case against him and Steel soon finds himself before his own hearing alleging misconduct in his pursuit of Slade but fortunately for Steel, a visit to Slade's old cell-mate yields results. Original episode and this adaptation inspired by the Billionaire Boys Club case.