Toby Jones plays former human rights solicitor Phil Shiner in the first trailer for BBC drama Danny Boy.
The one-off film stars Anthony Boyle as former colour sergeant Brian Wood, who was accused of war crimes in Iraq.
The drama follows the two men as they go head-to-head in a conflict that led to one of Britain’s biggest public inquiries, the Al-Sweady Inquiry.
It will explore the effect it had on Sgt Wood as well as his family: father and ex-soldier Gavin, played by Alex Ferns; mother Margaret, played by Pauline Turner; and wife Lucy, played by Leah McNamara.
The trailer shows Boyle as Sgt Wood, questioning his actions during the conflict, before asking his young son: “Do I look like a murderer to you?” while Jones can be seen saying: “British soldiers get away with murder.”
Sgt Wood was a lance corporal in the 1st Princess of Wales’s Royal Regiment at the Battle of Danny Boy in May 2004.
The battle sparked a 13-year legal fight after British troops were given an order to remove the bodies of the 20 Iraqi dead and take them back to a nearby camp along with nine prisoners of war.
The detainees, who were insurgents with the Shia militia Mahdi Army, went on to claim they had been mistreated and heard the torture and murder of their compatriots.
Among the dead was 19-year-old Hamid Al-Sweady, whose uncle Khuder Al-Sweady claimed he had been murdered at the British camp.
Mr Shiner was struck off from practising law after being found to have acted dishonestly in bringing murder and torture claims against Iraq war veterans.
Sgt Wood, one of five soldiers awarded the Military Cross for their actions during the Battle of Danny Boy, later described the legal process as an “ordeal”.
The drama is helmed by I May Destroy You director Sam Miller, who previously said: “The film is a candid and subtle delve into a troubled sequence in recent history that sets up an undertow threatening all those involved.
“The intimate questions raised about the nature of soldiering and the political ramifications are never more prescient.”
The drama will air on BBC Two later in the spring.