ANNA KENDRICK

and Blake Lively combine well in this stylish comedythriller. It remains captivating enough despite never entirely cohering.

Kendrick leads as Stephanie, a widowed, suburban single mum who posts instructional “mummy” videos on a YouTube-esque site. The story coyly teases impending twists from the get-go and Kendrick is as appealing as always, justifying the film’s use of her mummy vlogs as a narrative outlet.

When her young son makes a new friend at school, the boy’s mother, Emily (Lively), enters Stephanie’s life. She enlivens it, introducing her to day-drinking, a nice house, and a devastating wardrobe. Stephanie is awed by the glamorous, enigmatic Emily, who works in New York high fashion, and the pair quickly develop a confessional friendship.

When Emily invokes the title of the film, the plot turns begin unveiling themselves.

Just as Kendrick is perfectly

suited to her character’s wideeyed, enthusiastic innocence, Lively is highly convincing as the biting, unflappable Emily, a neofemme fatale in a pinstripe suit.

The bountiful chemistry between the two actors buoys the film when the plot falls short, as it occasionally does.

It’s an admirable and welcome goal on the part of director Paul Feig (Bridesmaids, Ghostbusters )to want to infuse a reasonably familiar “yuppies in peril” thriller with more laughs than we’re used to seeing in this context, but navigating the line between the darkness and the hilarity proves a tricky gambit.

Neither element fails particularly but there is a lack of elegance to their integration, especially in the film’s denouement.