Christopher Guest's "Family Tree" is growing. The improv comedy mastermind has been adding cast members to his upcoming mockumentary-style HBO series starring Chris O'Dowd as 30-year-old Tom Chadwick, who begins exploring his roots after receiving a box of belongings from a great aunt he'd never met.
While the first round of additions came from the pool of collaborators Guest has been working with in his films for years -- Ed Begley Jr. as Tom's Uncle Andy, Fred Willard as Andy's neighbor and Michael McKean as Tom's father Keith -- the latest actors to join the series include some newer faces from the indie-film world. According to Deadline, "Sun Don't Shine" director Amy Seimetz has been brought in for a recurring role as Ally, an aspiring writer and bookshop employee in Los Angeles whom Tom meets in unusual circumstances. Ventriloquist and "Her Master's Voice" director Nina Conti has been added as a regular in the part of Tom's sister, while Tom Bennett ("PhoneShop") will play Tom's best friend.
Additional new cast members include Matt Griesser as Greg, Tom's American cousin; Maria Blasucci as Greg’s girlfriend; and Lisa Palfrey as the wife of Tom’s father.
The eight-episode series is a British co-production and will air in the UK on BBC Two.