Y Ffilm: Ble Mae Cyw?

Gareth, Rachael, Heini, Tigi, Twm Tisian, Sali Mali and Jac y Jwc are going on a picnic. But Cyw seems to have disappeared. Has Rapsgaliwn got anything to do with this or is it one of Norman Price's silly pranks? Will the friends be able to find Cyw?