Do you remember that guy who took you to prom, who you later ditched for the guy you really wanted to go with (or at least the guy you would have ditched if you were starring in a Molly Ringwald movie)? You may not have given that first guy a second thought, but Michael Showalter remembered him. In fact, Showalter’s latest romantic comedy “The Baxter” is all about the guy you left behind.

In his directorial debut, Showalter also writes and stars as Elliot Sherman a.k.a. The Baxter. A “Baxter” is “the kind of guy you settle with because you can’t be with the one you love.” Elliot Wilbur Sherman is as exciting as toothpaste. The man reads the dictionary. For fun.

However, Showalter couples his flaws with an earnestness that makes the safe protagonist incredibly endearing. While Michael Showalter might not yet be a household name, his fans have obsessed over his cool camp counselor role in the 2001 cult-classic “Wet Hot American Summer,” his comedy trio “Stella” on Comedy Central, and the long-defunct MTV show “The State.”

The story of “The Baxter” begins at the end, with an uncertain Elliot waiting for his bride on the day of his wedding. In the scenes that follow, the unglamorous Elliot narrates the events that lead him to his precarious situation at the altar. A platonic romance begins when Elliot improbably meets magazine editor Caroline Swann (Elizabeth Banks) and somehow becomes her fiancé. When Bradley Lake (Justin Theroux of “Six Feet Under” ), the love of Caroline’s life, resurfaces shortly before the couple’s wedding, poor Elliot is overwhelmed by insecurity.

Cecil Mills (Michelle Williams) an oddball office temp by day and “singer” by night befriends Elliot. She also just happens to be the perfect woman for him (she’s read up to the G’s in dictionary), but of course he is too oblivious to throw caution to the Brooklyn winds and seize Cecil.

Showalter’s film succeeds because of its irresistible charm and quirkiness. The true credit to the film is the acting; many of Showalter’s former cast members (David Wain, Michael Ian Black, Elizabeth Banks, and Paul Rudd just to mention a few) of “Wet Hot American Summer” return for “The Baxter.” Michelle Williams has left her “Dawson’s Creek” days far behind, believable as awkward and loveable Cecil Mills. Justin Theroux, bizarre and oh-so-spooky in “Mulholland Drive,” steals several scenes, including a hilarious inversion of male machismo in which he cries in Elliot’s car lamenting how sensitive he is.

Unfortunately, one of the drawbacks of the film is its pacing and the endless reiteration that Elliot is not right for Caroline and he is The Baxter of all Baxters. For example, there’s Elliot’s mantra, “Compromise is the key to success,” Caroline’s Freudian slip when she introduces Elliot as her friend and Bradley as her fiancé, and Elliot’s hilarious if not pathetic plan to honeymoon at Yellowstone Park complete with “camping, fishing, and guided tours.”

Nonetheless if Showalter overcompensates, he only does it because of his exacting detail. Showalter exquisitely demonstrates Elliot’s desire for companionship just by showing the picture on Elliot’s coffee mug: two cats sitting on a window ledge. Styled after the screwball comedies of the past, the film has an undeniable 1940s vibe, and it lives in Elliot’s tweed coat, navy vest, and plaid newsboy cap. The result is a fresh but nostalgic wide-eyed wonder that leaves you mildly elated.

It is pretty clear from the beginning where this film goes; however, Showalter manages to make the trip worthwhile. Remember that, no matter who you are, you have had a Baxter moment. Whether you stayed up all night helping that pretty girl finish her problem set, who then didn’t remember your name the next day, or you tried in vain the catch the eye of that hot guy at last year’s party, Elliot’s story is familar, but well-told enough by Showalter to give everyone hope.