The fly-on-the-playroom wall documentary focuses on relationships, revealing how the four-year-olds form friendships, rivalries and romances with each other. Arthur and Iris decide to be boyfriend and girlfriend - only for Frankie to also show an interest in Iris. Best friends Na'Shae and Penny fall out over a hair bobble, and a five-metre climbing wall arrives at the nursery. Is anyone brave enough to make it all the way to the top?