Following the rescue of Kanan Jarrus in the Mustafar system, the Galactic Empire imposed a siege on the planet Lothal. Darth Vader, the Emperor's second-in-command intended to use the siege to ferret the elusive Lothal rebel cell out of hiding. This rebel cell consisted of the Twi'lek pilot Hera Syndulla, the former Jedi Padawan Kanan Jarrus, the astromech droid Chopper, the Lasat warrior Garazeb Orrelios, the Mandalorian weapons expert Sabine Wren, and the Lothalian Jedi apprentice Ezra Bridger. After deducing that the rebels had left Lothal, Vader realized that the rebels had to be drawn back to Lothal. An opportunity to draw the Spectres back to Lothal emerged when the Imperial Minister Maketh Tua initiated contact with the rebel cell through the auspices of the Ithorian bartender Old Jho.
Fearful of receiving punishment from Grand Moff Wilhuff Tarkin, Minister Tua had offered to defect to the rebellion in return for providing valuable intelligence on the Empire's operations on Lothal. After some discussion, the Spectres, who had by then joined forces with the Phoenix Cell, agreed to help Tua escape offworld. Since their starship Ghost was familiar to the local Imperial authorities, the Spectres opted to travel to the planet in a Star Commuter 2000 shuttle. Their plan was to rendezvous with Minister Tua in Capital City while she was scheduled to leave on a shuttle to meet with Governor Tarkin. Unknown to Tua, her movements were being monitored by an Imperial probe droid sent by Agent Kallus.
Putting their plans into action, the Spectres managed to slip past the Imperial blockade of Lothal. After being given clearance to land on Lothal, the rebels headed towards the planet's Capital City to rendezvous with Minister Tua. While Chopper and Zeb stayed aboard the Star Commuter shuttle to provide a quick exit, the other four rebels headed to their rendezvous point; which turned out to be a landing pad containing the shuttle. However, the rebels found that a number of Imperial stormtroopers were guarding the landing pad.
To enter the landing pad, Kanan assaulted a Stormtrooper Commander and stole his armor. Meanwhile Hera, Ezra, and Sabine hid on the rooftops to attack the Imperials from above. Shortly later, Minister Tua arrived with Agent Kallus in a landspeeder. Kallus had been personally sent by Darth Vader to guarantee her personal safety. After Tua and Kallus entered the landing pad with a disguised Kanan, the Spectres launched their attack. Kanan then took the opportunity to attack Kallus and his men.
Meanwhile, the other rebels rescued Tua and headed to the Imperial shuttle. Tua managed to enter the vessel. Before Hera could follow her, the shuttle was destroyed by a bomb, which threw both the rebels and stormtroopers backwards. In the presence of an Imperial probe droid, a seemingly outraged Agent Kallus lambasted the Spectres for "murdering" Minister Tua. The skirmish at the landing pad was observed by Darth Vader, who was pleased to see his plan unfolding.
The Spectres' mission to rescue Minister Maketh Tua was a failed operation that provided a propaganda boost to the Imperial authorities on Lothal. In an attempt to turn Lothal's population against the rebels, the Imperial broadcaster Alton Kastle claimed the rebels were "terrorists" who had murdered a public servant. The Spectres attempted to flee in their Star Commuter Shuttle but it was shot down by an AT-DP walker. The rebels then hid in the former Bridger household but were driven out by Imperial forces. With Imperial forces searching the streets of Capital City, the rebels decided to infiltrate the Imperial Headquarters on Lothal.
Putting their escape plan into action, the rebels managed to infiltrate the Imperial Headquarters and also found several deflector shield generators. They were about to leave the compound in an Imperial shuttle when they were confronted by Darth Vader. The Sith Lord bested Kanan and Ezra in a lightsaber duel but the rebels managed to escape following a fierce skirmish. With the help of Lando Calrissian, the rebels managed to escape offworld by using sensor buoys to baffle the orbiting Imperial fleet. Unknown to the Spectres however, Vader had arranged for their escape in order to use them to lead the Empire to the Phoenix rebel fleet in deep space. This led the Empire to launch a devastating attack on the Phoenix fleet.
The mission to Lothal first appeared in the one-hour television movie Star Wars Rebels: The Siege of Lothal, which first premiered at the Celebration Anaheim on April 18, 2015. It was later released on Disney XD on June 20, 2015.