I Danny, ei dad yw'r tad mwyaf rhyfeddol a chyffrous yn y byd. Mae bywyd yn hapus ac yn dawel yn eu carafan sipsi, ond un diwrnod mae Danny'n darganfod bod ei dad wedi bod yn torri'r gyfraith. Ar ben hynny, mae'n rhaid i Danny ymuno â'i dad cyn hir wrth iddyn nhw geisio rhoi cynllwyn mentrus a drygionus ar waith yn erbyn Mr Victor Hazell, dyn ofnadwy a chanddo wyneb mawr, coch... A Welsh adaptation of the well-loved Roald Dahl classic story of Danny and his father who outwit their greedy, rich neighbour, Mr Victor Hazell. Danny thinks his dad is the most marvellous and exciting father a boy could wish for. Life is happy and peaceful in their gipsy caravan, until one day Danny discovers his dad has been breaking the law.