Author: Rebecca Thomas.

'I will build you a castle here, to keep you safe forever.' Brycheiniog in the tenth century is a dangerous kingdom - so dangerous that the king's sister must be hidden from sight. Elwedd has not been allowed to leave the castle on the water for twelve years. On the island, she is safe. As she discovers the truth about the castle she is drawn into a battle for the whole kingdom.

Awdur: Rebecca Thomas.

'Fe wna i adeiladu castell yma i ti, i dy gadw'n ddiogel am byth.' Teyrnas beryglus yw Brycheiniog y ddegfed ganrif – mor beryglus fel bod rhaid cuddio chwaer y brenin o'r golwg. Nid yw Elwedd wedi cael gadael y castell ar y dŵr am ddeuddeng mlynedd. Ar yr ynys, mae'n ddiogel. Wrth geisio darganfod y gwir am y castell ar y dŵr, daw Elwedd i ganol brwydr am Frycheiniog gyfan.