The Sinatra Incident refers to the situation surrounding the "capture" of the Jedi Padawan Sinatra shortly after the first year of the Galaxial War in 46 ABY. Sinatra met Eliana on Kamino and agreed to journey to Ni'novia despite knowing she would be captured. Though not known at the time, she was doing this as part of an assassination plot to avenge her family name and kill Lord Apocalypse.
At first, Emperor Trivas was going to trade the Jedi girl for a ransom of 30 million Jedi Credits. However, the Sith Council was not in favor of this when rumor came that the Jedi Grand Master, Lucius Vos, was going to turn himself in. Knowing that the sly Grand Master would not have made that offer without having a plan, Trivas opposed this. Later, the Jedi Council Member, Zaria Secura, offered to turn herself in. Sensing that Zaria would not have any hidden plans, Trivas agreed to this.
Still, debate raged among both the Jedi and Sith leadership. Vos refused to let Zaria turn herself in and Trivas refused to let the Sith Council accept Vos. Finally, as the incident dragged on, more offers were made. Trivas offered to ransom Sinatra off for only 15 million credits. Then, when that proved to be unacceptable for the Sith Council, he gave up and turned the Jedi over to Lord Scyrone.
Before Scyrone could do anything with Sinatra, her brother Apocalypse betrayed the Sith and freed his sister. Unknown to the rest of the Sith, Trivas had planned for this and secretly helped the rogue Sith transport his sister to safety so that the entire incident would be settled. Scyrone hunted Apocalypse down and defeated him in a duel. Before he could be brought in for a trial, Apocalypse committed ritual suicide to prevent more disruption among the Sith. Sinatra safely escaped to meet up with Vos and the rest of the Jedi.