Mae'r heulwen gwanwyn yn dawnsio drwy'r coed yng nghysgod Castell Coch.

The spring sunshine dances through the trees in the shadow of Castell Coch.

Mae'r castell yn llawn o sŵn a phobol wrth i'r ŵyl ganol oesol fynd yn ei blaen.

The castle is full of noise and people as the medieval festival goes on.

Mae cerddoriaeth gynnar yn cymysgu â sgwrsiadau hapus y dorf.

Early music mixes with the happy chatter of the crowd.

Ond un person, Gareth, ni all ymlacio.

But one person, Gareth, cannot relax.

Mae Gareth yn ymgolli yn hanes y castell.

Gareth is immersed in the history of the castle.

Mae'n wirfoddolwr brwdfrydig sy'n gwybod pob carreg a chornel.

He is an enthusiastic volunteer who knows every stone and corner.

Mae'n dyheu am ddod o hyd i drysor coll sy'n gwneud enw iddo'i hun.

He longs to find lost treasure that would make a name for himself.

Heddiw, yn erbyn y cefndir bywiog o bobl mewn gwisgoedd arwrol, mae ei gyfle wedi cyrraedd.

Today, against the lively backdrop of people in heroic costumes, his opportunity has arrived.

Arddangosir arteffact gwerthfawr o'r enw Amrediad Arthur yn y castell.

A valuable artifact called Amrediad Arthur is on display in the castle.

Wrth groesi'r llaith llawr cerrig, mae'n cwrdd â Ceri, ditectif lleol sydd wedi dod gyda'i theulu.

While crossing the damp stone floor, he meets Ceri, a local detective who has come with her family.

Ond wrth fynd ymlaen mae hi'n cael ei dal mewn dirgelwch.

But as they move forward, she finds herself caught in a mystery.

Mae'r arteffact hyd yn oed yn fwy diddorol na'r sioeau.

The artifact is even more interesting than the shows.

Mae'n cael ei hannog i ymchwilio.

She is encouraged to investigate.

Darllenodd diwrnod o'r blaen am dynged tywyll sy'n gysylltiedig â'r arteffact, a phobl yn dechrau poeni.

She read the previous day about a dark fate associated with the artifact, and people are beginning to worry.

Ond mae Gareth, yn credu'n gryf fod rhaid datrys y problemau hyn.

But Gareth, strongly believes that these problems need to be solved.

"Mae angen eich help arna i," meddai wrth Ceri.

"I need your help," he said to Ceri.

Er ei amheuaeth gychwynnol, penderfynodd Ceri ymuno â Gareth.

Despite her initial skepticism, Ceri decided to join Gareth.

Efallai bod truth yn yr hen chwedlau yma.

Maybe there is truth in these old legends.

Mae'r ddau yn cwrdd ag Eira, perfformiwr sifalri dirgel sy'n cyfrannu at draethawd y digwyddiad.

The two meet Eira, a mysterious chivalry performer who contributes to the narrative of the event.

Mae'n deall rhywbeth, rhywbeth na fyddai eraill yn sylwi.

She understands something, something that others would not notice.

Ond mae hefyd yn eithaf disglair, na fyddai neb mor hawdd ymddiried.

But she is also quite bright, not someone easily trusted.

Mae gan Eira wybodaeth dadeni am mythoc o amgylch yr arteffact.

Eira has renaissance knowledge about the myth surrounding the artifact.

Wrth iddynt symud drwy'r castell, canfu Gareth fynedfa gudd wrth gefn y stablau bren.

As they move through the castle, Gareth discovers a hidden entrance at the back of the wooden stables.

"Dewch!

"Come!"

" meddai wrth Ceri.

he says to Ceri.

Mae'r ddau yn llithro i lawr grisiau tywyll i ddarganfod ystafell gudd.

The two slide down dark stairs to discover a hidden room.

Mae'r arteffact yno, wedi'i baratoi gan Eira, ond nid ar gyfer dwyn, i amddiffyn yr arteffact o'r "melltith".

The artifact is there, prepared by Eira, but not for stealing, to protect the artifact from the "curse."

Mae'r cwbl yn datrys yn ystod perfformiad mawr y wyl.

Everything unfolds during the festival's main performance.

Mae Gareth a Ceri yn dangos oll i'r wyl o flaen y dorf achawonog.

Gareth and Ceri reveal all to the festival in front of the noble crowd.

Mae Eira yn cydnabod ei hachos - i gadw'r arteffact yn ddiogel o'r clychau.

Eira acknowledges her case - to keep the artifact safe from the bells.

Mae'r gyhoedd yn anfodlon am eu rhybuddion doniol kan ysbyty Eira, ond mae Gareth yn colli'i amheuaeth.

The public is displeased by their humorous warnings over Eira's theatrics, but Gareth sheds his skepticism.

Tân gwefr yn ffrwydro yn nhadau'r torfeydd.

Fireworks explode in the crowd's applause.

Mae Gareth yn derbyn clod am ei ddewrder, ac i'r neges a dogma a geir iddo.

Gareth receives praise for his bravery, and for the message and purpose given to him.

Mae hyd yn oed Ceri'n teimlo'n barch tuag at ei benderfyniad.

Even Ceri feels respect for his determination.

Ar ddiwedd y dydd, mae'r cyhoeddiad yn pyrmio rhyw, a'r artifact yn mynd yn ôl i'w safle yn ddiogel - a Gareth gyda chalon lwythog.

At the end of the day, the proclamation excites everyone, and the artifact returns safely to its place - and Gareth with a full heart.