Daniel Radcliffe is set to explore his family connections to Northern Ireland in the latest series of the BBC's Who Do You Think You Are?
During the programme, the Harry Potter star travels to Banbridge in County Down, where his father grew up.
While there, he uncovers that four of his great-great-uncles fought in World War One.
Radcliffe reveals in the programme that one of them was an inspiration for his role in My Boy Jack.
Ernest McDowell proves to be a key focus of the programme, which will be aired on Monday.
The 29-year-old actor travels to Dromore to meet his aunt Linda, who still lives in the town, and is shown family pictures.
The images are of Ernest, his three other great-great-uncles and his great-grandmother Flo - whom the actor did not previously know he had met when he was a baby.
Radcliffe is also given a bundle of letters written by and to Ernest, which had been kept by his great-grandmother.
The letters underline the importance of written correspondence writing during World War One.
When reading them, the actor discovers the extent to which Ernest went to reassure his mother that he was alright during the war, something he describes as "extraordinary".
Amongst them are some love letters sent to Ernie by someone called Jeannie.
"We will get them all a good day when we are getting married, won't we love?" one letter reads.
Other letters reveal Ernest's injuries during the war, including being shot and contracting frostbite, before Radcliffe discovers that his great-great-uncle did not survive.
In a letter sent to Ernest's mother by a soldier who was with him at the front, it details "your boy and two more chaps from Belfast" were killed when a shell landed in a dug-out.
"A lot of very sad things have happened to various parts of my family but I can't be sad about it because everyone was loved," says Radcliffe.
"Ultimately that means that, even if their time on earth ended prematurely and sadly, it was worth having."
During the programme Radcliffe also travels to north London where he explores his ancestry on his maternal side.
You can watch the programme in full on Monday 22nd July at 21:00 BST on BBC One.