Retired detective Alex Ridley re-enters the gritty world of crime to lend his expertise as police consultant to Carol and Goodwin with a perplexing case involving a spate of jewellery raids, but the complexity deepens when a crucial witness on the brink of exposing vital information about the criminal gang responsible is killed. As the team discovers connections to a stud farm and a local middleman in the drug trade, Ridley races against time to decipher the motives of the case.