Issue number twenty-one of the Marvel comic book series Star Wars, titled Star Wars 21, marks the beginning of the The Last Flight of the Harbinger story arc. This comic, which debuted on July 20, 2016, was penned by Jason Aaron and features artwork by Jorge Molina. Readers are introduced to a fresh stormtrooper squad commanded by Sergeant Kreel, a character previously seen in the second arc of the same comic series.
As the Imperial shuttle, having been shot down by the Taylander shuttle, crash-lands on the Ghost Moon, Kreel recounts his past, detailing the events that befell his people on his home planet of Chagar IX. He recalls witnessing a man's death at the age of four, crying inconsolably, and then seeing countless more die. Two years later, his own father was murdered before his eyes. A week later, he himself became a killer. His entire life on his home world revolved around the fighting pits, for the wealthy spectators in the stands and for those too impoverished to escape the arena. He assumed this would be his life until his death. However, one day, everything changed irrevocably. On that day, Kreel beheld the most beautiful sight he had ever witnessed: his first stormtrooper.
During Kreel's recollection, after the rebel shuttle crashed, the rebels fled as the Imperial shuttle landed. Emerging from the shuttle was the elite stormtrooper squad, the 501st Legion, known as Task Force 99, also referred to as the SCAR Squadron, dispatched to hunt down the rebels.
Upon inspecting the Taylander shuttle, Sharp reports that the Rebels have vanished. Sergeant Kreel informs Mic that their target is on board, prompting Mic to state that they had time to destroy the computers, and he instructs Cav to track their trail. The SCAR Squad then begins searching for the rebels within the deserted town. Aero informs Zuke that they are on the "Ghost Moon," a location evacuated years ago due to volcanic eruptions. He remarks to Zuke, "a good place to hide, if you're a Rebel coward." However, Kreel counters that they are not hiding, but leading them into an ambush.
Using electrobinoculars, the sergeant questions Misty about the situation. Misty replies that they would already be dead if the Rebel snipers were competent, adding that they are fortunate the snipers are "rubbish". Misty continues that the "rubbish sniper'd" is probably on the top floor. They go another click, and he'll have them in range. Kreel instructs Cav to accompany him while the others advance, remaining out of range. Cav questions Kreel about taking the stairs, but Kreel responds that "SCAR Troopers don't need stairs," implying their use of rocket jets. They eliminate four Rebel snipers, and when a fifth sniper exclaims, "May the Force be with me!" before repeating, he misses the fire.
Kreel tells Zuke that he's all his, so Zuke fires a missile launcher at the base of the building, killing the fifth Rebel sniper. Kreel continues his narration, reflecting on his destiny to die in the arena, like his parents and everyone he knew. That was until the stormtroopers arrived, the Empire made life worth living. As the Empire arrived on his home world of Chagar IX and toppled the overlords in a day and shut down the arenas, especially that they gave his people jobs and peace.
Kreel orders the rest of the squad to continue moving, following the sound of blaster fire. Misty expresses confusion, as Kreel, Cav, and Zuke begin firing upon other Rebel troopers, with the rest of the squad joining in. Aero hot-wires and repairs an old speeder bike. Kreel continues his story that he will be old enough as they will give him something even greater. At the Imperial Academy, he befriended a ranger named Izak Anzio, a farmer's boy from Agamar who dreamed of seeing the galaxy. During their first mission, Izak never made it off the rebel mortars that they killed him. So, Kreel killed every rebel he could find that day, and every day since. The rebels them to think they're fighting for freedom. He knew that the rebels lied, since the Empire came as "Freedom means law. Freedom means order. All the rebels want is chaos." The mission of SCAR Squadron is to eliminate terrorists, permanently.
During their pursuit, at the bridge, they pushed the Rebels and their bike down to the lava, until they were ambushed by the Rebels' tank, Micro tells Zuke to do something but Zuke can't to pierce the tank's armor. Kreel orders his squad to retreat into the sewage tunnels.
While concealed within the sewage tunnels to evade the rebel armored tank, Mic notes that their previous sergeant never led them through the sewers. Kreel continues to narrate that he goes deep under cover on Nar Shaddaa for his special assignment that he spent a few years. He got caught by a dianoga the trash squid as it narrates that their last sergeant was with them for years, still waiting for him to prove himself, or waiting for him to die. Kreel defeated the dianoga and continues to hunt down the rebels in the sewers.
The rebels are reported that they're not on surface and have to wait for the trash squid to get them, but the two of them have been shot by SCAR Squad, as Admiral Verette orders to take them down to the sewers by using the detonators. As it explodes, they've been caught the blast of the rebel tank, and the cannon of the rebel tank have been sliced by Kreel's lightsaber, in which that he finishes his narrate of his story that he didn't talk to the others about his childhood in the arena, during his undercover. They don't know that he picked up a few special skills along the way, and he feels that their old sergeant couldn't do this. Cav was surprised that Kreel is holding a lightsaber as Kreel ordered to get the Rebels out of the tank.
Sharp using the flamethrower on the rebel tank to force the Rebels out of the tank. As Admiral Verette, and a Rebel trooper are out of the tank, the trooper protects the admiral while he tries to get away from the SCAR Squad, but the trooper got killed and Verette have been injured, as Verette have been captured by the SCAR Squad as they prepared for an interrogation.