The brothers unveil their biggest and best enclosure yet, a huge new habitat for the Amur tiger sisters Aleena and Siberia. The boys test out the new 80,000-gallon swimming pool and get hands-on as they prepare to move the world's biggest cats.

Temperatures rise as the zoo is hit by a heatwave. Many of the animals are well adapted to the sun, but those from cooler climates need extra attention. The boys devise a series of ingenious tricks to keep each animal cool, including ice baths.

It's health check day and the boys give each of the animals a thorough MOT. Tamara the tapir gets a pedicure, Marion the tortoise gets a shell rub and the keepers discover a worrying lump on Luna the reindeer's leg.

The One Zoo Three brothers are on a mission to compose a zoo musical using the sounds of the animals. Lar gibbons Shany and Raff swing into action and audition to be the perfect percussionists, while a health check with Bombura the loud kookaburra sees him in with a shout for lead vocals. Even playful jaguar cub Inka proves she can add a cracking big crunch to the mix!