After Suyin and her twin sons were arrested by Kuvira for attempting a sneak attack on her and Baatar and Huan refused to acknowledge the metalbender as Zaofu's rightful leader, they were all imprisoned in a cavern underneath the factory where Kuvira was building a spirit energy cannon. Opal and Lin tried to convince the world leaders to launch an attack on Kuvira, though after they refused, Lin and Opal planned to rescue their family by themselves. Bolin accompanied them as well in his efforts to repair his relationship with Opal.
Arriving at Zaofu, Toph approached Lin, Opal, and Bolin and alerted them that all the prisoners had been moved out of the metal city and to a nearby prison camp. Following Bolin's directions, the foursome made their way over to the facility, where they discovered with seismic sense that the Beifongs were held in an underground cavern. As they overheard that there would be a demonstration of the spirit vine cannon in the presence of all the factory workers and soldiers, the group decided to use the moment of the test to infiltrate the base and save their family.Overpowering the few guards still patrolling the premises, Lin, Toph, and Bolin made their way down to the cavern, while Opal stood guard outside, communicating with them via a radio. Finding the family suspended inside a wooden cell, Lin ordered her mother and Bolin to catapult her toward the prison, where she used a metal blade to cut an opening through the wood. One by one, she swung the prisoners with her cables over the chasm to be caught by Bolin. However, when only Baatar and Suyin remained, they were discovered, since the architect was afraid of heights and screamed while being swung to safety. A mecha suit opened fire at Lin and Suyin, though Lin managed to evade the attack by severing the ropes that suspended the cell, letting it swing back to where the rest of their family was awaiting them. Despite the alarm having been sounded, the group managed to reach the surface, where they reunited with Opal. However, as she told them that Zhu Li had been sentenced to die in the abandoned town by a shot of the cannon, Bolin left to save her, followed by Opal on Juicy, while Lin, Suyin, Wei, and Wing decided to try to take out Kuvira's new cannon.
A family versus an empireEditOpal and Bolin did not manage to free Zhu Li before the spirit energy cannon was fire, though they were saved when Lin, Suyin, Wei, and Wing used their earthbending to disrupt the cannon's aim. After a fierce exchange of attacks between the Beifongs and Kuvira's army, both parties hid behind earthen walls. Suyin used these as a distraction, however, to reach Kuvira standing atop her cannon and engage her in battle. After exchanging several blows, the younger metalbender managed to throw Suyin off the cannon, though before her army could apprehend Suyin once again, the woman was saved by Wei, who retreated with her into the protective circle Wing and Lin had erected. The earthbending soldiers broke through that barrier, however, though before they could apprehend the foursome, they and the mecha suits were all toppled over when Toph arrived and shifted the earth underneath their feet. At that moment, Opal, Bolin, and Zhu Li arrived with Juicy, allowing everyone to escape to safety on the flying bison.
Somewhere safe, Suyin and Lin thanked their mother for her interference and Lin and Toph reconciled their differences that had caused them not to speak with each other for twenty years. Opal also forgave Bolin for his affiliation with Kuvira, thus reestablishing their relationship. Zhu Li interrupted the joyous reunion, however, as she was adamant about reaching Republic City as soon as possible, since she had inside information that Kuvira planned on attacking the metropolis two weeks later.