Stori am Charlie Challinor, plentyn ifanc sy’n delio â nifer o broblemau yn ei bywyd. Gwaethygwyd y rhain pan ofynnir iddo ofalu am genau bach o’r enw Cadno. Ond, mae rhywbeth yn dilyn Cadno, helgwn cas, gan ei fod yn genau unigryw: maent yn ‘firefox’. Felly, bydd rhaid i Charlie amddiffyn o oddi ar y bygythiad yma, os ydy o’n ddigon ddewr i’w wneud.

Charlie Challinor’s life is a bit scary. Between bullies at school and big changes at home, every day brings a new challenge, and Charlie’s not sure he’s got enough bravery to face them on his own.

But when a mysterious boy leaves him in charge of a mischievous cub called Cadno, everything changes. Because Cadno is no ordinary fox, he’s a firefox – and something sinister is on his trail.

As a giant black hound starts sniffing round his home town, Charlie realises only he can protect the last firefox. And that maybe he’s brave enough to do that after all…