Fred, a young girl, and her Grandpa travel to the island of Papa-Nupi to see, or rather hear, the mysterious Tub-Tub - a plant that flowers every 200 years and which 'produces music so beautiful even the birds in the trees stop singing to hear it.' But even if they can get there, can they manage to bring a recording back with them to prove what they've heard?

Mae Fred a'i thad-cu yn teithio i ynys Papa-Nupi i weld, neu'n hytrach i glywed y Tub-Tub, sef planhigyn sy'n blodeuo bob 200 mlynedd, ac sy'n cynhyrchu cerddoriaeth mor hardd fel bo'r adar yn y coed yn peidio canu eu hunain er mwyn ei glywed. Ond os medran nhw gyrraedd yr ynys, a fyddan nhw'n llwyddo i wneud recordiad o gân y planhigyn i brofi yr hyn a glywson nhw?