Happythankyoumoreplease, a Manhattan romcom starring, written, and directed by Josh Radnor (Ted on How I Met Your Mother), is a case of when bad scripts happen to good actors. Given its similarities to a bygone sitcom, one might call it Friends without benefits.

The film shares much in common with Radnor's character, Sam, a gifted short-story writer who has yet to master long form. While individual scenes are appealing, the movie does not cohere.

Its three central characters are at that awkward age: too old for casual relations and not ready to commit.

Sam is a writer circulating the manuscript of his first novel, The Other Great Thing About Vinyl, and strictly a one-night-stand kind of guy. His friend Mary Catherine (Zoe Kazan) has a boyfriend who wants to move to L.A. His best friend, Annie (Malin Akerman), isn't over her ex.

Sam is irresponsible on so many levels that it sabotages the movie.

On the subway to meet with his literary agent, Sam rescues a young boy, Rasheen (Michael Algieri), separated from his companions. When Sam finds that Rasheen is at odds with his foster parents, he takes the boy in without notifying authorities.

Rasheen is not a character, but a plot device. Sam uses Rasheen to ingratiate himself with Mississippi (Kate Mara, sister of Rooney), a flirty redheaded bartender, and to create third-act complications.

The performers are likable and their attitude is fundamentally sunny. But in happythankyoumoreplease (which takes its title from a cabdriver's affirmation of gratitude) the plausibility quotient is so low that though you like some of the characters, you don't believe in them.