“Outlander” has cast two pivotal roles for Season 3, Variety has learned.

Joining Jamie Fraser’s (Sam Heughan) world in the 18th century, John Bell (“The Hobbit: The Battle of the Five Armies”) will play the role of Young Ian Murray, Jamie’s nephew. Young Ian is a tall, gangly Scottish lad with a heart of gold, a stubborn streak and a penchant for getting into trouble. Bursting with charm, he’s more like his adventurous, fierce uncle Jamie than his farmer father Ian — but when we meet him, he is still a very gawky boy. However, he keeps trying to prove that he is a man and we will see him grow into quite a formidable one as the series evolves.

Meanwhile, in Claire’s (Caitriona Balfe) life in 20th Century Boston, Wil Johnson (“Waking the Dead”) will play her friend and medical colleague, Joe Abernathy. Joe is a fellow doctor-in-training whom Claire befriends in medical school. Intelligent, charismatic, with a wry and irreverent sense of humor, Joe is a loyal confidant with great affection for Claire. He puts on a good face, but he is all too aware of his place in the Civil Rights era. Joe and Claire both feel out of place in the mostly all-white, all-male medical field, which bonds them together in a lifelong friendship.

Season 3 of Starz’s “Outlander” is based on the third novel in Diana Gabaldon’s bestselling series, “Voyager.” The third season picks up right after Claire travels through the stones to return to her life in 1948. Now pregnant, she struggles with the fallout of her sudden reappearance and its effect on her marriage to her first husband, Frank (Tobias Menzies). Meanwhile, in the 18th century, Jamie suffers from the aftermath of his doomed last stand at the historic battle of Culloden, as well as the loss of Claire. As the years pass, Jamie and Claire attempt to make a life apart from one another, each haunted by the memory of their lost love. The budding possibility that Claire can return to Jamie in the past breathes new hope into Claire’s heart… as well as new doubt. Separated by continents and centuries, Claire and Jamie must find their way back to each other. As always, adversity, mystery and adventure await them on the path to reunion. And the question remains: When they find each other, will they be the same people who parted at the standing stones, all those years ago?

Showrunner Ronald D. Moore, Maril Davis, Matthew B. Roberts, Toni Graphia, Anne Kenney and Andy Harries serve as executive producers of “Outlander,” which is produced by Tall Ship Productions, Story Mining & Supply Company and Left Bank Pictures in association with Sony Pictures Television. Starz retains all domestic multiplatform pay TV rights to the original series.