The central character is Tom Chadwick (Bridesmaid's Chris O'Dowd), whose life in his hometown of London hasn't been as fulfilling as he would like, since his long-term girlfriend recently devestated him and he has no job or prospects on the horizon. When Tom visits his aspiring-inventor father (Michael McKean), who loves broad cheesy British sitcoms (which are all fake by the way, created specifically for the show) and remarried an eccentric foreigner named Luba, he learns about a great-aunt Victoria who just died and left him a box full of photographs and other small heirlooms. With little else going on his life, Tom delves into the box to learn about his ancestry, taking some of the items to a local antique shop where the owner (Jim Piddock, who co-writes the show with Guest) provides him with some history and directs him where else he should go to learn more about his family. A misleading photo suggests Tom's great-grandfather is a prestigious military man, but he soon discovers that he was only a small-time actor who often played the rear end of a pantomime horse. Another photograph reveals that his grandfather was a participant in the poorest Olympic Games ever, and a visit to his country cousins uncovers the secret behind a riff that developed between them and his family.
Tom's discovery that his great-great-grandfather was actually born in the US is what really allows the series to pick up greater comedic momentum, as Tom meets eccentric American cousins played by Ed Begley Jr. and Christopher Guest, who hail from Los Angeles and North Carolina respectively (the always hilarious Fred Willard also appears as Begley's obnoxious neighbor). Once there, Tom reaches out to Civil War reenactors to solve a mystery involving two separate pictures of their great-great-grandfather, one featuring him dressed as a union soldier and the other as a confederate. Of course the answer opens up new doors into their heritage. The cast is rounded out by Tom's dopey, but loyal, childhood friend Pete (Tom Bennett), whose always good for a laugh, as well as Tom's quirky older sister Bea and her pal Monkey (Nina Conti). You see Bea had a traumatic zoo experience as a child, so a therapist had her communicate via a monkey puppet, and she's used him ever since as her "inner voice," aka a way for her to be crude and say whatever she's thinking (Conti is an excellent ventriloquist and, for the most part, Monk is treated as his own witty character). Much has been made about Bea and Monk being the most entertaining regular cast members, or even the only reason worth watching, and while I might disagree on those finer points there's no denying that they are a hilarious pair that provide many of the series' laugh-out-loud moments. However, if you give Family Tree a chance and stick around for the whole season (which is probably best watched binge-style), you'll come to appreciate its subtle brand of eccentric family comedy for yourself.