Following the Imperial attack on Garel, the Phoenix Cell was searching for a remote world to establish a permanent rebel base, with help from the Spectres. Two of these rebels were the Great Jedi Purge survivor Kanan Jarrus and his apprentice Ezra Bridger. As Jedi, they were constantly being hunted by the Galactic Empire's Inquisitors. Two of these Inquisitors, the Fifth Brother and the Seventh Sister, pursued Kanan and Ezra for several months; hampering the rebellion's efforts to search for a base.
In 3 BBY, Kanan and Ezra along with the astromech droid Chopper visited the stormy planet of Oosalon. They were scouting the planet as a possible location for a rebel base. While Kanan and Ezra were exploring the Oosalon Mesa, they were attacked by the Fifth Brother and the Seventh Sister. A lightsaber duel ensued between the two groups of opponents. The two Jedi tried to contact Chopper, who was flying the auxiliary ship Phantom but received no response. During the duel, the Jedi managed to destroy one of the Seventh Sister's ID9 seeker droids. As the duel progressed, the Fifth Brother used the Force to shove Ezra off a cliff. However, Kanan managed to levitate his apprentice to safety and grab his hand.
Continuing their fight with the Inquisitors, Ezra used the Force to summon a large tibidee. The apprentice and master leapt off the clip and escaped on the back of the tibidee which flew them to safety. Once airborne, they were picked up by Chopper and the Phantom. The rebels then departed into space on the Phantom. While traveling through hyperspace, Kanan arranged with Hera Syndulla and the other crew of the Ghost to meet them in deep space in order to protect Phoenix Cell from the Empire's agents.
Entrance of the Jedi Temple on Lothal
After reuniting with their team aboard the Ghost, Kanan confided in Hera that the Inquisitors were making it hard for him and Ezra to help the rebellion to establish a base, fearing that he and Ezra would have to part company with the rebellion. Later, the two Jedi met with the former Jedi Padawan Ahsoka Tano who counselled them to seek advice from Master Yoda at the Jedi Temple on Lothal. Parting company with the other rebels, the Jedi, Ahsoka, and Chopper traveled on the Phantom to Lothal. While Chopper waited outside, the Jedi and Ahsoka entered the temple.
There, Kanan completed his Jedi Trials and became a Jedi Knight. Meanwhile, Ezra met with Yoda who counselled the young Jedi not to fight or they would be destroyed. Since Ezra was committed to supporting the rebellion, Yoda counselled Ezra and his companions to find the planet Malachor. Meanwhile, Ahsoka experienced a Force vision of her former mentor Anakin Skywalker and learnt that he had indeed become Darth Vader. The three managed to flee with Chopper shortly before the Seventh Sister and the Fifth Brother breached the temple. After helping the rebellion to establish Chopper Base, the two Jedi, Chopper and Ahsoka departed for their journey to Malachor.
The Duel on Oosalon served as the exposition of the Star Wars Rebels episode "Shroud of Darkness," which first premiered on March 2, 2016.