the lovers have arranged a
code of signals, and it is agreed that as soon as the light
in Ysolde's window is extinguished her lover will join her as
speedily as possible.

It is a beautiful summer night, and the last echoes of
the hunting horn are dying away on the evening breeze, when
Ysolde turns to Brangeane, and impatiently bids her put out the
light. The terrified nurse refuses to do so, and implores Ysolde
not to summon her lover, declaring that she is sure that Melot,
one of the king's courtiers, noted her pallor and Tristan's
strange embarrassment. In vain she adds that she knows his
suspicions have been aroused, and that he is keeping close watch
over them both to denounce them should they do anything amiss.
Ysolde refuses to believe her.

The princess is so happy that she makes fun of her attendant's
forebodings, and, after praising the tender passion she feels,
she again bids her put out the light. As Brangeane will not
obey this command, Ysolde, too much in love to wait any longer,
finally extinguishes the light with her own hand, and bids her
nurse go up in the watch-tower and keep a sharp lookout.

Ysolde then hastens to the open door, and gazes anxiously out
into the twilighted forest, frantically waving her veil to
hasten the coming of her lover, and runs to meet and embrace
him when at last he appears.

Blissful in each other's company, Tristan and Ysolde now forget
all else, while they exchange passionate vows and declarations
of love, bewailing the length of the days which keep them apart,
and the shortness of the nights during which they can see each
other. In a passionate duet of mutual love and admiration,
they also rejoice that, instead of dying together, as Ysolde
had planned, they are still able to live and love.

Brangeane, posted in the watch-tower above, repeatedly warns them
that they had better part, but her wise advice proves useless,
and it is only when she utters a loud cry of alarm that Tristan
and Ysolde start apart. Simultaneously almost with Brangeane's
cry, Kurvenal rushes upon the scene with drawn sword, imploring
his master to fly; but ere this advice can be followed King
Mark and the traitor Melot appear, closely followed by all
the royal hunting party. Ysolde, overcome with shame at being
thus detected with her lover, sinks fainting to the ground,
while Tristan, wishing to shield her as much as possible from
the scornful glances of these men, stands in front of her wit