Based on

Movies like Heart and Sword (1998)

After the death of his father, prince Tristan is living in Cornwall at the court of his uncle, King Marke, who treats him like a son. When the Irish king sends his son Morold over to demand high tax payments, Tristan challenges him to combat. He manages to kill Morold but is very badly injured, and is placed in a boat to be healed by the magic powers of the sea, which takes him across to Ireland.