For her school biology project Sophie is growing a sample of bacteria. Emma thinks its just a blob of mouldy yoghurt and wipes it away, before realising what she's done. In an effort to recreate the blob, Emma asks Adil to wish up a new one. But the new blob has a mind of its own. It wants to play, and it's hungry, too. As the blob eats everything in sight that's pink, it begins to grow, and grow and grow.