Starring Anna Kendrick. Rated PG

An extremely thin notion gets off to a pleasant start, thanks to an amiable cast. The lightweight movie was written by the writing-acting-directing Duplass brothers, Mark and Jay, mumblecore veterans who went on to mainstream fare like HBO’s Togetherness series.

Their reputation must have helped convince busy Anna Kendrick to take on the throwaway role of Eloise, a neurotic with no specified skills or job who reluctantly attends the wedding of an old friend, despite being recently jilted by the woman’s dopey brother (Wyatt Russell, son of Kurt Russell and Goldie Hawn).

Eloise’s precarious association causes her to be seated with the “randoms” at a lakeside-hotel wedding party. Random is right, as the guests appear to be chosen more for acting talent, visual diversity, and availability than any logical connections to the story. Playing an anxious Brit on furlough from jail, Hello Ladies’ Lurch-size Stephen Merchant sits next to The Grand Budapest Hotel’s miniature Tony Revolori, as a horny, socially awkward teen.

Across from them are Craig Robinson and Lisa Kudrow, as a couple going through a bad patch, and Nebraska’s June Squibb, a former nanny to the rich siblings at the sort-of story’s centre. I know why the nanny and Eloise are there, but damned if I can remember why the others are.

Despite being far from the action, or because of it, these losers start yakking it up. Almost half of the 90-minute movie is devoted to free-flowing, playlike banter, and this (plus the inexpensive one-month shoot, in Georgia) must have attracted Kendrick and company. The table starts collapsing right in the middle, however, when Eloise meets a dashing stranger (Australia’s Thomas Cocquerel), and everyone starts divulging secrets at the top of their lungs.

Easy-to-please director Jeffrey Blitz, veteran of The Office and of the Oscar-nominated doc Spellbound, doesn’t bother with niceties like having the wedding combo sound like it’s playing in the room. And he asks us to take sudden dramatic turns seriously when the actors were doing pratfalls in the previous scene. Eloise’s first impulse, to stay away, was probably wise.