“Maggie’s Plan” offers a reasonable imitation of a quality romantic screwball comedy, with all the requisite elements of a fine entry in a storied tradition.

It simply doesn’t hold up to scrutiny, though, with a narrative that uncomfortably transitions from a lighthearted, charming place to one that defies any objective standard of how people interact with each other.

Writer-director Rebecca Miller crafts an intriguing character in Maggie (Greta Gerwig), an intelligent and lonely Manhattanite committed to having a baby on her own, until her carefully-crafted life is interrupted by chaos when married professor John (Ethan Hawke) falls in love with her.

In an all-too-rare occurrence in this genre, or any other, really, the woman in a romance is bestowed with soulful complications while the man in question remains something of a befuddling dope.

Gerwig, with an appealing blend of strength and sweetness that’s more assured than her norm, keeps us engaged with the character even as the screenplay forces her to engage in asinine contortions in Maggie’s eventual plot to extricate herself from John’s life as their romance goes cold. The movie, straddling a line between authentic observation and a strained wallow in the foibles of the city’s intelligentsia, lets her down.