Wife of King Cichoriades of Cornwall.
Her husband locked her up in a tower because she was adulterous. Joene’s lover appeared at the foot of the tower, and Cichoriades started climbing down the tower from a rope in order to fight with him. The crafty Joene cut the rope from the top, and her husband fell to his death. With her lover, she fled to North Wales.
Joene’s father was King Gonosor of Ireland and her sister was Queen Gloriande of Lyonesse.
Source
Prose Tristan | 1230-1240