Bookish 12-year-old Bird (Jade Pettyjohn) is sent into a spin when she experiences her first period in embarrassingly public circumstances.

Matters aren’t helped by her scatty single mother Jenny (Katee Sackhoff), who is next to useless at putting her at ease.

A comedy about menstruation might not sound the most beguiling prospect, but this coming-of-age indie movie from actress-turned-first-time writer-director Dorie Barton proves utterly charming.

Pettyjohn is a delight as the precocious Bird, constantly exasperated by her mother’s fecklessness and fed up that she has to be the grown-up in their relationship.

Sackhoff, meanwhile, makes the irresponsible Jenny funny as well as annoying and always ensures that we never lose sight of her essential good nature.