Ar fore braf haf, Carys, y tywysydd penderfynol, ar y tu blaen.

On a fine summer's day, Carys, the determined guide, was at the forefront.

Roedd hi'n arwain grŵp o dwristiaid drwy Gastell Caerdydd.

She was leading a group of tourists through Cardiff Castle.

Roedd yr awyr yn glir, a'r haul yn tywynnu dros y cerrig hynafol.

The sky was clear, and the sun shone on the ancient stones.

Roedd Rhodri, twrist brwdfrydig, ymysg y grŵp.

Among the group was Rhodri, an enthusiastic tourist.

Roedd ganddo gyfrinach: roedd e'n dda iawn am ddatrys posau.

He had a secret: he was very good at solving puzzles.

"Ewch ymlaen i ddwnsiwn y castell," meddai Carys.

"Proceed to the castle dungeon," said Carys.

Seiniodd ei llais yn yr oergell i bawb.

Her voice echoed through the chill, reaching everyone.

Roedd pethau nhw'r dwnsiwn yn dywyll a llawn hud.

The dungeon was dark and full of magic.

Caeodd yr ysgafn drws tu ôl iddynt.

The heavy door closed behind them.

"Pa mor diddorol yw hyn!" medd Rhodri i'w hunan.

"How interesting is this!" Rhodri murmured to himself.

Ond yn sydyn, clywodd pawb clic mawr.

But suddenly, everyone heard a loud click.

Roedd y drws yn gaedig.

The door was locked.

Cyffroi digolledig ddod trwy'r grŵp.

Uneasy excitement spread through the group.

"Gwnewch yn dawel pawb," meddai Carys yn dawel.

"Stay calm everyone," Carys said quietly.

"Gallwn ni ddelio â hyn."

"We can deal with this."

Edrychodd i Rhodri.

She looked at Rhodri.

Roedd e'n edrych yn chwilfrydig.

He appeared curious.

"Rhodri, wyt ti'n dda am ddatrys posau, on'd wyt ti?" gofynnodd hi.

"Rhodri, you're good at solving puzzles, aren't you?" she asked.

Gwŷdd Rhodri.

Rhodri nodded.

Teimlai ychydig o ymfalchïol wrth gerdded ymlaen.

He felt a bit proud as he stepped forward.

"Byddwn yn trio," meddai o.

"I'll try," he said.

Cyd-dynodd Rhodri ag archwilio'r waliau.

Rhodri began examining the walls.

Canfu orchuddiad y waliau gyda symbolau a rhiciau wedi'u cysgodi dros amser.

He found that they were covered with symbols and engravings shaded by time.

"Edrychwch yma," meddai Rhodri.

"Look here," he said.

"Mae'n edrych fel pos."

"It looks like a puzzle."

Egniodd Carys a'i helpu drwyddo.

Carys lit up and helped him.

Gweithiwyd gyda chynghrair agor ffigyrau hynafol y gwenithfaen.

They worked together to decipher the ancient granite figures.

Gafaelodd Rhodri yn sigred a throdd dro wrth dro.

Rhodri carefully turned the key bit by bit.

Ar wahân i'w synnu, teimlodd cyffyrddiad clic yn y ddinas.

To his surprise, he felt a click in the mechanism.

Roedd y drws wedi agor!

The door had opened!

Crio daeth o'r grŵp.

Cheers erupted from the group.

"Da iawn, Rhodri!" meddai Carys.

"Well done, Rhodri!" said Carys.

Y ddau esgynodd y tu allan yn saff.

They both emerged safely outside.

Roedd y grŵp yn edrych arnynt mewn brafder.

The group looked at them admiringly.

Roedd y touroddwr wrth ei bodd.

The tour guide was delighted.

"Diolch," meddai Rhodri yn swrth.

"Thanks," Rhodri said shyly.

"Efallai... hoffet ti' bach o goffi gydâ fi un diwrnod?"

"Maybe... would you like to have some coffee with me someday?"

Chwarddodd Carys.

Carys laughed.

"Byddwn i wrth fy modd," meddai hi.

"I'd love that," she said.

Trwy'r profiad hwnnw, deallodd Carys bod gellir delio ag unrhyw siŵrwydd gyda help.

Through that experience, Carys realized that any challenge could be overcome with help.

Teimlodd Rhodri'n fwy hyderus am ei alluoedd i ddatrys posau.

Rhodri felt more confident in his puzzle-solving abilities.

Roedd y dydd yn mynd heibio, ond y coffi cyntaf? Roedd hynny'n stori newydd i ddechrau.

The day went by, but the first coffee? That was a new story to begin.