The Detectives: Taking Down an OCG returns for a fourth series this time focusing on a specialist police unit in Rochdale and their multi-layered battle to bring down one of Greater Manchester's most notorious Organised Crime Groups (OCG).Told across three episodes and made over three years with a truly unprecedented depth of access, this compelling and shocking series follows the police operation as it gathers pace and grows in scale to encompass multiple cases, including drug supply, abduction, money laundering, attempted murder and the grooming of children as drug dealers.