When Cynan sees a dazzling rainbow, he is determined to help it shine forever. Guided by his friends, he chases it through the dripping wood... but the rainbow soon starts to fade. Once the last scrap of colour is gone, Cynan feels he has failed - until he realises something wonderful! A Welsh adaptation by Anwen Pierce of Fletcher and the Rainbow.

Pan wêl Cynan enfys lachar, mae'n benderfynol o'i helpu i ddisgleirio am byth. Gydag arweiniad ei ffrindiau, mae'n ymlid yr enfys drwy'r goedwig ddiferol... ond mae'r enfys yn dechrau diflannu. Cyn gynted ag y bo'r diferyn olaf o liw wedi cilio, mae Cynan yn teimlo ei fod wedi methu - hyd nes iddo sylweddoli rhywbeth rhyfeddol. Addasiad Cymraeg.