Long before The Office, Parks and Recreation, and Modern Family turned the mockumentary into a sitcom staple, Christopher Guest cornered the genre on the silver screen. With comedy classics like Best in Show, Waiting for Guffman, This is Spinal Tap, and A Mighty Wind under his belt, it’s no surprise that Guest decided to bring his brand of entertainment to television.

With Family Tree, Guest and co-writer/creator Jim Piddock have taken his classic formula and squeezed it down to a thirty-minute episode format for HBO, turning it into a clever semi-improvised comedy following that single-camera “interview” style.

Chris O’Dowd plays Tom Chadwick, an average man who visits home when his great aunt Victoria passes away. In her will, she leaves him a mysterious trunk full of family heirlooms, with no explanation. Tom, a child of divorce who grew up with his mother in Ireland, while his sister and father lived in London, knows little to nothing about his family’s history. He takes great pleasure in going through the chest and unraveling his genealogical roots, item by item, relative by relative, and in turn, piecing together his own identity.

As Tom, O’Dowd is charming, funny and endearing, but you cannot help but think you have seen his character before. It’s all too possible that this is O’Dowd’s bumbling, lovestruck cop from Bridesmaids trying to find his family, not someone entirely new. This is not necessarily a bad thing (who doesn’t like Chris O’Dowd?), because it’s very telling of Tom’s character; he’s just an average dude. He needs this box more than ever to help him figure out who he truly is, and that’s a great testament to O’Dowd’s acting.

Tom’s dead relatives are only a small part of his puzzle. His immediate family, comprised of sister Bea (Nina Conti), father Keith (Michael McKean) and stepmother Luba (Lisa Palfrey), is a bit more bizarre than your usual sitcom brood. Bea, traumatized from a childhood incident that is best left explained by her character in the pilot, has taken to channeling her emotions through the constant use of a monkey puppet (Monk). Monk says all the (usually negative) things that Bea is thinking out loud, to the point where it is as if she cannot control Monk’s actions. Luba is from a country of mysterious origins, and the grown Chadwick children have learned to tune out their stepmother’s eccentricities. She keeps their father happy, after all.

The writing is warm and comfortable in a fashion that keeps you just intrigued enough for another episode, but you’re not going to be rolling in the aisles after a viewing. The show definitely has its laugh out loud moments. Fans of Christopher Guest will easily recognize scenes where the actors improvise their lines; these are the stronger parts of each episode, by far, as you can tell even the actors are excited to be a part of the game. Tom, who is getting over a recent heartbreak, goes on a series of dates throughout the show. These improvised scenes get increasingly bizarre and uncomfortable; one girl cheerfully talks about her love of bones as he quietly weeps across the table.

For fans of Christopher Guest and his particular brand of comedy, Family Tree may be a runaway hit. But for others unfamiliar with this genre, the new HBO comedy may seem a bit slow or dry for American humor.

Family Tree premieres Sunday, May 12 at 10:30 ET/PT on HBO