King Marke leads a hunting party out into the night, leaving Isolde and Brangäne alone in the castle, who both stand beside a burning brazier. Isolde, listening to the hunting horns, believes several times that the hunting party is far enough away to warrant the extinguishing of the brazier – the prearranged signal for Tristan to join her ("Nicht Hörnerschall tönt so hold"). Brangäne warns Isolde that Melot, one of King Marke's knights, has seen the amorous looks exchanged between Tristan and Isolde and suspects their passion ("Ein Einz'ger war's, ich achtet' es wohl"). Isolde, however, believes Melot to be Tristan's most loyal friend, and, in a frenzy of desire, extinguishes the flames. Brangäne retires to the ramparts to keep watch as Tristan arrives.