There’s a storm a-coming: Hurricane Hector is bearing down on Miami and upbeat zookeeper Bonnie is cheerfully readying the animals at Cherokee Valley Zoo for when the heavens open. From ushering the flamingos into the urinals, where the sturdy brickwork will keep them safe, to wrestling boas into cages, it’s a Herculean task, but Bonnie is relentlessly chipper in the face of her labours.

Meanwhile, equally stoic but altogether more gruff Yorkshire bat expert, Carol, is presenting a tiny specimen to a classful of children. As brittle and misanthropic as Bonnie is warm and gregarious, they seem literal and figurative worlds apart. But as Bonnie battens down the hatches we see in flashback how these unlikely lasses met and became best of friends, and how that friendship galvanises Bonnie for the coming storm.

Written by Lily Bevan (who plays Bonnie) with a wry eye for human comedy, great gag lines, and a wellspring of empathy, Zoo manages the neat trick of being laugh out loud funny, and slowly, sneakily moving. On the surface preoccupied with the absurdity of the animal kingdom, it offers some of the sharpest character observation at this year’s Fringe.

Bevan’s Bonnie has clear depth, wounded beneath her wilfully sunny façade, while Lorna Beckett imbues the abrupt Carol with underlying warmth. She has impeccable comic delivery, and sparks off Bevan brilliantly. Both characters feel at once plausibly individual and endearingly familiar – you know people like this, and you have more than a little affection for them, even when their peculiarities drive you nuts.

For those seeking a buoyant odd-couple comedy, you’ll find it here. But it also has an easy depth, and you’ll come away reflecting on the transformative power of friendship, and just quite how resilient women can be in the face of life’s trials. Heartily recommended.