The story depicted is from Malory's Morte d'Arthur. In love with Sir Tristram but promised in marriage to King Mark, Iseult tries to kill herself but is prevented from doing so by King Mark, who grips her arm and forces her to drop the sword.

Burne-Jones's watercolours often make heavy use of gum arabic in the dark areas, creating a density and richness more often associated with oil painting than with watercolour.