King Marke and his men are hunting at night. His castle is empty except for Isolde and Brangaene who stand by a lighted torch. Isolde keeps thinking that the hunting horns are far enough away for her to put out the flames, giving the sign for Tristan to join her. Brangaene warns Isolde that one of King Marke’s knights, Melot, has seen Tristan and Isolde looking at one another lovingly. Isolde, however, thinks that Melot is Tristan’s best friend, and, desperate to see Tristan, she puts out the flames. Brangaene goes to the castle walls to keep a look-out as Tristan arrives.