This book is so cinematic, it is practically sitting up and begging to become a New Adult rom-com, coming soon to a theater near you. It is also a shaggy dog story --- two shaggy dogs, to be exact. Twenty-three-year-old Jonathan Trefoil, a Midwesterner transplanted to New York City, agrees to a six-month stint caring for his brother’s canine companions --- Dante, a border collie, and a cocker spaniel, Sissy --- and his life changes. He is unleashed.

But not right away. When we first meet Jonathan, he still has enough angst to fill a St. Bernard’s water bowl. He has all the markers of successful adulthood: a longtime and now long-distance girlfriend; a dreary-yet-statusy copywriting job at a hip Tribeca advertising agency called Comrade (the décor includes a Communist-era Russian railway station); and a pretty nice one-bedroom on the Lower East Side (this, to my mind, is the least realistic part of the novel, as most New Yorkers under 50 now live in another borough). But Jonathan doesn’t feel like an adult; plus, he worries that the dogs aren’t happy. “Dante should be herding sheep, at the very least,” he tells his attractive vet, Dr. Clare. “And Sissy…she doesn’t complain, but I often get a sense that she’s missing something. Grouse?”

Jonathan’s inner life is quite different (cue the animated portion of the movie I’m imagining). He and his childhood best friend/co-worker, Max, have always loved comics; on the side he is working on a graphic novel, The New York Inferno, in which “a border collie spirit guide accompanies a young poet through the nine circles of the New York underworld.” Jonathan is a latter-day Walter Mitty, as his mind tends to veer off into fantasy and gallop away on a tangent. This tendency to riff at the drop of a hat is sometimes an annoying tic (it slows the narrative), but it can also be endearing. Struggling to characterize his dogs’ state of mind, he comes up with angst, ennui and weltschmerz, then wonders why the relevant words exist only in German and French: “Was the English language so uninterested in descriptions of spiritual disquiet?” His take on weird names is good, too: “How did a kid get through life with a name like Lark Rise Heaven Halo? Jonathan supposed that these days it wouldn’t be so bad. Her classmates would be called things like Stetson, Mona Lisa, Jedi, and Albania.”

"I learned from Rosoff’s bio that she herself has two 'very hairy' dogs, and it shows in her affectionate and witty portrayal of Jonathan’s four-legged roommates."

The dogs are a Greek chorus and deus ex machina combined --- witnesses to Jonathan’s flailing efforts to grow up as well as behind-the-scenes plotters --- but the major engine of the story is his girlfriend. Julie has been working in the Midwest for Bridal-360, a glossy magazine and online wedding planner. Now, promoted to a position in the New York office,she moves in with Jonathan and tries to apply her super-organized template to his life. Naturally, she doesn’t get along with the intrinsically untidy dogs --- or, really, with Jonathan himself. Nevertheless, they agree to get married in a live-streamed online ceremony that will be featured in Bridal-360. His reason is lame: “[B[eing married is so amazingly grown up. I’m tired of being just some amorphous man-child thing.” Her reason is unsentimental: “I’m used to you.”

Will Dante and Sissy pull off an intervention that gets Jonathan to (a) break up with Julie, (b) leave his stultifying job, and (c) find himself --- and them --- another, better companion? You might as well ask if Lassie came home. What would be an unlikely coincidence in an ordinary romantic comedy here becomes a canine conspiracy involving faked symptoms, dog-run set-ups and guileless looks.

Rosoff is best known for her prize-winning young adult novels, three of which I have read and loved (HOW I LIVE NOW, PICTURE ME GONE and WHAT I WAS); this is her first adult fiction. It’s a rollicking picaresque novel, a sort of 21st-century Tom Jones that shifts jauntily from scene to scene but never entirely drew me in. Her YA novels have humor, too, but not at the expense of deeper feeling. They put kids in testing situations where they have to grow up, survive, make choices and find meaning.

Jonathan, though older, goes through a similar process. However, whereas Rosoff’s adolescent protagonists are fresh and unclichéd, he tends to resemble the sort of charming, compulsively ironic, somewhat nerdy leading man we’ve seen a lot of in movies (think a more recent version of Hugh Grant). Indeed, almost all the characters, though fun, are a bit one-dimensional: Max, the Don Juan with a heart of gold; Julie, the control freak; and Dr. Clare, the cool Brit (with a heart of gold). Plus: the clueless parents; the foul, porno-loving boss; and the Zen, gender-unspecific office PA.

I just feel that Rosoff sometimes goes for the obvious when a more subtle idea would have served the book better. I’m thinking of Jonathan’s tendency to say funeral when he means wedding in the run-up to the ceremony; the surreally disastrous wedding itself; a presentation at Comrade that explodes in a slapstick-ish scene; and the journey into the countryside to “find himself” (cue the slo-mo and a song that will be nominated for an Academy Award). Didn’t we just see this movie at the neighborhood multiplex? The one with reclining seats?

But I loved the book anyway, for its constant beat of sardonic humor, and for Dante and Sissy, who are priceless. I learned from Rosoff’s bio that she herself has two “very hairy” dogs, and it shows in her affectionate and witty portrayal of Jonathan’s four-legged roommates. The dogs stir Jonathan’s nutty imagination and steal his heart --- and they stole mine, too. While I didn’t care deeply which of four (four!) possible romantic interests he wound up with, I did care that he love, honor and obey (plus feed and walk) his shaggy companions. In return, the book’s ending implies, there’s every chance that they will give him (sorry) a new leash on life.