Director Sam Mendes has made a career documenting the decline and fall of marriages and families, most famously in his Academy Award-winning American Beauty and just recently with Revolutionary Road, starring his wife, Kate Winslet. Your mileage may vary on the profundity of these downbeat suburban dramas, but Mendes has certainly found a successful and esteemed niche.

Which is part of what makes Away We Go, scripted by real-life married couple Dave Eggers and Vendela Vida, such a surprise. There are touches of anxiety and doubt throughout, but Away We Go is nevertheless hopeful about the prospects of a young couple a few months shy of their first baby.

That couple is Burt (John Krasinski of The Office) and Verona (Maya Rudolph of Saturday Night Live), and though they never plan to marry it is clear they intend to spend their lives together. Their life plans are thrown in flux when Burt’s parents, played with absent-minded hilarity by Jeff Daniels and Catherine O’Hara, announce they’ll be moving to Barcelona, Spain, immediately. “Just for a couple years.”

Freed of any ties to their current home, Burt and Verona set out across the country to scout out a new place to call home. Away We Go is thus both a road movie and an anthology movie, with its format allowing for Burt and Verona to work out their trepidations about parenthood (and being real, true adults) while seeing how their friends and family have coped with the same difficulties.

It’s a bittersweet mix, sometimes absurd, often hilarious, and occasionally sad. Burt and Verona’s first stop is a disaster: Verona’s loudmouth former boss (Allison Janney) and nonsensical, conspiracy-minded husband (Jim Gaffigan) aren’t the sort of people you’d want around your own kids, never mind listen to how they’re raising their own. Other stops are equally unsuccessful, and Burt and Verona’s insecurities come to a head when they hear about the disintegration of Burt’s brother Courtney’s (Paul Schneider) marriage.

The couple does, of course, find a place that they can call home. We knew they would from the beginning, because the simple comfort of their relationship—conveyed with deceptive ease by Krasinski and especially Rudolph, who remains grounded even when her husband goofs off—is strong.

Their low-key chemistry is welcome in a movie that invites the outlandish at every turn. Burt and Verona aren’t a traditional family, do not hail from them, and know few people who do—and yet no big fuss is made of this. The characters understand intrinsically (as Eggers, Vida, and Mendes do) that “family” is often fluid—and that the nuclear ideal is often just a fantasy.

It’s a wise movie that can acknowledge this simple truth without making a fuss over it, and a rare one that can also be entertaining and genuine. Away We Go isn’t a revelatory movie, but it is perceptive in its portrait of the birth of a family.