|“||All right, here's what we're looking at, folks. Step one: Travel undetected to Eagle Island. Step two: We're gonna break into the super-weapon. And step three: deactivate the superweapon!||”|
While Zeta was attempting to destroy both Bird Island and Piggy Island to expand her frozen, tropical paradise on Eagle Island with a powerful superweapon, the newly formed Bird-Pig alliance dispatched its special forces on a mission to destroy such superweapon, with time running out and the fate of their homelands at stake. After a great struggle with Zeta's forces, the special forces destroyed the superweapon just as Zeta was about to use it at full power, and convinced Zeta to abandon her plans for a three-island resort and instead live a married life with Mighty Eagle like before.
|“||All right, guys, do not worry. We got this. Red here has got your back. And your front and your sides.||”|
— Red, The Angry Birds Movie 2
Meanwhile, after noticing that the attack on Mighty Eagle's cave didn't convince the islands' inhabitants to flee, Zeta decides to order her scientists to begin modifying her superweapon so that it could shoot deadly lava-ice balls that would inflict maximum destruction.
Traveling to the island undetected
|“||This is it? This is the amazing team I've been working around the clock for?||”|
— Garry, The Angry Birds Movie 2
The Bird-Pig special forces began traveling to Eagle Island in Leonard's giant pig submarine. Onboard it, they meet Garry, a master Pig inventor and head of the Piggy Gadget Lab, who then shows the team various inventions that could be useful in completing the mission, including invisi-spray and an eagle detector. Red criticizes the effectiveness of the gadgets, prompting Silver to take him aside and urge him to be more supportive instead of trying to call the shots all the time. As the special forces team continues en route to their target, Zeta observes the scientists' work and notices some setbacks, prompting her to make clear that she wants the upgrade ready in less than 24 hours and those who fail would suffer the same fate as Steve.
Before long, the submarine finally arrives at the shores of Eagle Island, using her powerful engine and hull to smash through an ice sheet. The special forces team arrive wearing winter coats, walked out onto the island through the submarine's front hatch, but end up slipping across it. After they recover, Mighty Eagle, who came along for the ride, tells the rest of the team that he can't personally face Zeta, revealing that she was his ex-girlfriend and explaining how she ended up becoming evil, to the shock of the team, before flying back to what was left of his cave to contemplate.
Divided and nearly conquered
|“||Uh, guys? I 100 percent believe in you and this Harvey idea, but I think this one's gonna need me.||”|
— Silver, The Angry Birds Movie 2
the mission with whatever they had. Still caught up with wanting to be the hero, Red begins staging his own daring plan to stop Zeta, climbing the volcano where the superweapon was housed without any eagle guards noticing him. Silver, concerned for Red's safety, goes after him, while the rest of the team enters and controls Harvey to infiltrate the base.
After Red takes a long way to get to the top, Silver beats him there and tries to reason with Red over what he was doing, but is unsuccessful. Seeing that the superweapon relied on a power source that would be its fatal weakness to exploit, Red then decides to bungee-jump down to the cannon to reach it and would have killed himself had Silver not took quick action to secure the line. The rope proves too short, leaving Red hanging in mid-air. He tries to swing to one side of the spiraling ice ball tracks, but cannot do so by himself until Silver gives him a push, before having to bungee right down to catch a feather from him that could have caught a guard's attention. Red and Silver then sneak the rest of the way down to the cannon floor and then to what Red thinks is the power cord connecting the cannon and cuts it, only to discover that it's for a microwave. The two are then noticed by Hank, the toughest Eagle guard, and are unfortunately subdued and captured.Meanwhile, the rest of the special forces inside Harvey successfully convince Carl and Jerry to let them all in, appearing as a new hire. The team's eagle detector goes off but is quickly silenced, and they discover that a key card is needed to get inside the main cannon chamber. They end up getting one by sneaking into a bathroom and taking one from Brad, whom they accidentally knock out in the process, then walk right inside the cannon chamber. Axel, one of the guards, challenges them to a break-dancing battle that has all the eagle guards dancing in excitement, causing them to forget what they were supposed to do. As they were all dancing, Chuck notices that Red and Silver ended up getting caught and out of desperation ends up accidentally destroying Harvey. Knowing that they don't have a moment to spare before they are noticed and caught like the two of them, the remaining special forces retreat and lock themselves in a room before the eagles get back to guard duty.
Running out of time
|“||There's no turning back! The future we deserve is about to be ours! Glenn! Activate the weapon! Start the countdown.||”|
— Zeta, The Angry Birds Movie 2
Shortly after Zeta leaves Red and Silver alone in captivity, Red then finally explains to Silver that he made his reckless plan just because he feared that he would fall out of favor if he didn't have a significant role in the mission. Zeta announces in a speech to her eagles that her weapon is nearly ready, her dreams of better living space were close at hand and all she needs is ten minutes to ensure she has enough ammunition to deliver a full-scale bombardment of both islands. During the speech, Red and Silver struggle to wriggle free from their recliners for several seconds in a futile attempt to escape, until Silver discovers that she could use her crest-braids to snag her recliner's air cap and rip it open, deflating it and freeing herself. As she works to free Red, the remainder of their allies, having found a way to get inside Zeta's room without running into any guards, makes an explosive entry with Bomb to finish doing so.
The regrouped Bird-Pig special forces make sense of their new situation, with Red agreeing to allow Silver to take command for the rest of the mission so that she could come up with a better plan to save the day within what little time they had. The plan would be to have Chuck and Bomb distract the guards, so that Red and Silver can get to the superweapon's bubble-freezing machine and freeze themselves inside a ball that they can use to crush the cannon once it reaches a sufficient speed, with the Pigs providing the force to launch the ball into the cannon by cutting off the spiral track with a manual wall switch discovered.
Destroying the superweapon
|“|| Silver: Time for Plan X.
Leonard: Plan X? I thought you said spandex.
— The Angry Birds Movie 2
At the bubble-freezing machine, Red and Silver leap at a given time to freeze themselves inside a ball to take control of it. They dodge the lava injectors on the way down the spiral track and get a workout into building up speed with it. However, even though they reach Silver's mandatory speed of 65 miles per hour, the Pigs are unable to use the switch to cut off the track, which breaks. With time running out, the special forces thinks of a way to improvise and end up having Chuck running over to the track to take the gadget from Garry, only to have him throw it up into the air after being hit by a ball, whereupon it lands in Leonard's hooves. He passes the device to Courtney, who manages to put the device right in front of Red and Silver's iceball to derail it. The ball as hoped sails towards the cannon just as the weapon becomes ready to launch, but fails to crush the cannon, shattering and sending Red and Silver tumbling in front of eagle guards waiting to capture them again. They also appear to round up the entire team as well.
Silver is devastated to see that her plan failed too and Zeta mocks the team for their failure, but before she could fire the weapon, Mighty Eagle arrives and makes an impassioned plea to attack him instead of the islands, or at least reconsider their lost romance. This delay gives Silver an opportunity to make a plan C to destroy the weapon by calling on Chuck to tie her superweapon across the cannon muzzle. Zeta then rejects Mighty Eagle again and then finally fires the weapon, only to see the missiles snared by a strand of Silver's superstring. The line threatens to sever, but just then, three hatchlings, Zoe, Samantha and Vincent and three piglets all aboard a pig-shaped hot air balloon happen to be near where it ripped high above the volcano and manage to grab both frayed ends while linking hands together to prevent the line from coming apart. They hold it long enough so that the missiles fall back into the cannon, destroying Zeta's superweapon and the base and prompting everyone to flee. Debbie would have been killed from the impact of the destruction had Mighty Eagle not shielded her from it. Grateful for his protective move, she accepts him as her true father and Mighty Eagle convinces a remorseful Zeta, regretting her actions, to abandon her plans for a three-island resort, rekindle her romance and go forward with marrying him at long last.
|“||Thank you, guys. Thank you for this. And for all the support and love. You know, it means...Well, it means everything to me. But, um, I don't deserve it. Silver does.||”|
— Red, The Angry Birds Movie 2
The head portion of Harvey was salvaged and later used by Zoe, Sam and Vincent to re-enact the battle against Zeta, inspired by the actions of the heroes they unwittingly assisted.