The face-off between DI Kate Fleming and PC Ryan Pilkington wasn't the only explosive moment in last week's episode five of Line of Duty – we were also introduced to a brand new key character.
In episode five, Marcus Thurwell was revealed to be a former police detective and a crucial player in AC-12's case of exposing a ring of corrupt high-level police officers and their collusion with organised crime. And the actor playing him? None other than James Nesbitt!
We can't wait to see what more the actor brings to the show. So who is his mysterious character, Marcus Thurwell? Here's all we know…
WATCH: HELLO! Insider breaks down episode five of Line of Duty
Marcus Thurwell is a former senior detective and uncovered by AC-12 as being the Senior Investigating Officer in the Oliver Stephens-Lloyd case – an investigation into child sexual abuse at Sands View Boys Home (think series three and Danny Waldron).
Oliver, a social worker, came forward to report the crimes but was later found dead. His death was ruled as a suicide, however AC-12 believe it could have been murder. Fun fact: Marcus Thurwell was in fact mentioned in paper during series three, so this series is not the first we've heard of him.
In addition, his name was also mentioned in relation to the 2003 case of Lawrence Christopher, who was attacked by racist thugs and later died in police custody at the hands of police officers.
Marcus' connection to both cases is crucial. Not only was he the Senior Investigating Officer of both these highly sensitive cases, but it was these two cases that investigative journalist Gail Vella was digging into in order to expose police collusion with organised crime. We now know, of course, that Gail was murdered – and many believe for her silence.
James Nesbitt as Marcus Thurwell
It's not just Marcus' connection to these two incidents that proved to be key for AC-12. DC Chloe Bishop and DI Steve Arnott also found that a number of police officers were involved in both cases, too, that prove that police corruption is rife.
DCI Ian Buckells and former senior officer Patrick Fairbank were also named as being part of each case, as well as newly appointed Chief Constable Philip Osbourne.
Both these cases are of interest to AC-12. The Sands View case has seen no justice brought to the boys that were abused, and none of the police officers involved in the death of Lawrence Christopher faced consequences.
Instead, they were given early retirement – as was SIO Marcus Thurwell, who relocated to Spain. Meaning that both cases have high-levels of police corruption surrounding them. Could Marcus be the key to finally exposing the crime ring and the mysterious H once and for all? We can't wait to find out…
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.