Who Do You Think You Are? - Season 15

Our Girl actress Michelle Keegan uncovers some exceptional women on her family tree.

Actress Olivia Colman claims to be 'the least adventurous person I know.' As for her ancestors, apart from a rumour that there was a Frenchwoman somewhere in her family tree, Olivia thinks they are largely from Norfolk. Olivia is astonished to discover that she needs to travel to India to find out more about her great-great-great-grandmother Harriot.

Olivia finds records that reveal Harriot was an orphan in 1811 on a ship bound for England from (then) Calcutta. Harriot's father was an an Englishman, but the identity of her mother, who gave birth to her in a remote Indian village, is a mystery Olivia delights in solving.

Comedian Lee Mack was born Lee McKillop in the north of England, just like his McKillop great-grandfather, who was also a comedian, known as Billy Mac. Lee has a few playbills from Billy Mac's variety hall performances, but knows little more about him. Not long into his journey, Lee discovers that his great-grandfather was passionate about more than making people laugh. Billy Mac joined the first ever pals battalion in Liverpool at the start of the First World War and honed his act at the front lines in the Battle of the Somme.

Lee is also curious about his maternal grandad Joe's upbringing - deserted by his unwed mother and raised by his grandparents in County Mayo at the time of the Irish Civil War.

Iconic pop star Boy George grew up in south London in an Irish family. George expects to find a lot of sadness in his family tree. He knows that his maternal grandmother was found wandering the streets of Dublin as a small child and put in a children's home and wants to find out how she came to be in such a dire situation. He's also heard that another ancestor was hanged in Dublin's Mountjoy Gaol and is somehow connected to Kevin Barry who was commemorated in a well-known Irish rebel song. As George uncovers the grim details of what really happened to his grandmother and his great uncle, he also delights in a new sense of his family being truly part of Irish history.

Strictly Come Dancing's head judge Shirley Ballas investigates a family story that her maternal great-grandmother abandoned her husband and children for a more exciting life in America. What Shirley discovers casts her great-grandmother in a completely new light.

On her father's side, Shirley pursues a rumour that she has black ancestors - a trail which leads her to colonial Cape Town and the era of slave trafficking to South Africa via the Indian Ocean.

DJ, presenter and former member of boy band JLS, Marvin Humes delves into his Jamaican and his English heritage, and finds exceptional stories on both sides of the family. Deep in the Jamaican countryside, Marvin's discoveries about the lives of his black ancestors during the time of slavery turn his expectations upside down. In England, Marvin's follows the trail of his great-grandfather about whom he knows almost nothing. But Marvin's research reveals a hero, who overcame a traumatic childhood to play a part in one of the most dramatic events of the Second World War.

Robert 'Judge' Rinder follows the story of his grandfather, a Holocaust survivor, hearing first-hand testimony of the horror of Nazi forced labour camps as well as of the hope offered by a new life in Lake Windermere. Investigating the dark mystery surrounding his great-grandfather leads Robert to a small town in Latvia, where he uncovers a story of mental illness and trauma which will ultimately, he hopes, lay some ghosts to rest.

Paralympic gold medal winner Jonnie Peacock looks back through the generations and ends up captivated by his four-times-great-grandmother.