Paper Heart / If the sneaky, charming Paper Heart, winner of the big screenwriting award at this year’s Sundance Film Festival, doesn’t put a big huge grin on your face, then, bunky, you’re little more than an inglorious bastard (sic).

Co-written by and starring Charlyne Yi (the stoner in Knocked Up) and a pitch-perfect, never better Michael Cera, Heart is part real doc, part fake doc, part love fable, part road movie and part puppet show. As co-written and directed by Nick Jasenovec (played on-camera by Jake Johnson), it’s almost impossible to tell the real from the fake; but the point is, of course, so is telling true love from ersatz love.

Charlyne, playing a version of herself, says she doesn’t know what love is, so Jasenovec arranges a doc in which Yi travels to l2 states, Canada (Vancouver) and Paris, interviewing 50 people from playground kids to people married 50 years to the just-now married to the happily divorced to a bear gay couple to a Vegas Elvis impersonator who owns a wedding chapel. Every couple has its own version of what love is–and how you can tell it for sure. Some of these stories are so compelling that Yi tells them through puppetry episodes, puppets she makes herself from her performance art shows back in the day. These inspired episodes are like nothing you’ve seen before, increasingly funny as this improbable movie continues to gain comic momentum.

Early on, Yi and her director go to some kind of party (probably staged for the movie) in which they bump into a slimmed-down Seth Rogen and hang out with some show-biz wannabes. Yi, at 23, has had a measure of success but nothing like the next celebrant–thin, smooth Michael Cera, who becomes, from time to time, part of the documentary team. And, yes, Yi and Cera fall in love, slowly and uncertainly, and develop a “relationship,” two loners dressed in geek-chic thrift shop clothing and afraid they don’t know if their slow-cooked togetherness is the real turtle soup or the mock.

As a real doc tech crew shoot scenes for the fake doc (but which exactly is which?), the Yi-Cera hook-up begins to develop its vicissitudes. Are they just using each other? Finally, disaster strikes and Cera, hurt and fed up, goes back home to Vancouver. Disconsolate, Yi follows, and so do the real and fake film crew.

All the real people Yi interviews, from Oklahoma biker bar habitués to a judge and his bride of 30 years to a psychic/fortune teller to a new married couple, the guy at least 40 years older than his giddy bride, to a romance counselor–all say true love is possible. But Yi has her doubts, even though her life, real and fake, has changed.

So what has happened? Has Yi learned anything about love? Do she and Cera get back together? You won’t find out here, but let it be said, loud and clear, that this fey, winsome and sometimes downright hilarious movie, a hall of mirrors perfectly reflecting the puzzlements of relationships, is a true original–and a beautiful fake.

In other words, it’s just like life.