Original: The Senate tries Sextus as Titus waits impatiently, sure that his friend will be exonerated; but the Senate finds him guilty, and an anguished Titus must sign Sextus' death sentence.
Simplified: The Senate take a court case against Sextus as Titus waits impatiently, sure that his friend will be found not guilty; but the Senate finds him guilty, and a terribly sad Titus must sign Sextus' death papers.