Watch Tristan and Isolde Full Movie Free Online 123Movies. A tragedy about the immoral love between the Cornish knight Tristan and the Irish princess Iseut/Isolde. It depicts Tristan's mission to escort Iseult from Ireland to Cornwall to marry his uncle, King Mark of Cornwall. On the journey, Tristan and Iseult ingest a love potion, which instigates a forbidden love affair between them.