|A New Defender|
|Air date||October 13, 2017|
|Written by||Tim Hedrick|
|Directed by||Steve In Chang Ahn|
Forces of good and evil converge on the planet Naxzela, where Voltron faces unforeseen danger only one Paladin can help them escape.
Lotor passes a remote beacon, and Zarcon pursues him to the unstable star Naveer 5, where Lotor evades Zarcon's cruisers by diving through the corona of the star and causing the pursuing cruisers' engines to overheat. They continue to track him as he outdistances them..
Haggar has arrived at Naxzela, but stops some distance away. She begins a ritual to destroy the planet.
Voltron is drawn to the surface of Naxzela, as huge pylons begin to rise all over the planet. As they activate, creating a force field enclosing the whole planet, Allura feels a wave of darkness. Voltron is forced down to his knees. He cannot escape the gravity, and slams back to ground. The team leaves the robot to find out what is keeping them grounded. Pidge determines that no energy source on the planet is powering the field, and they descend to the planet's core to discover an Altean terraforming plant. Allura attempts to shut it down and is strongly rebuffed. Hunk realizes that the floor of the chamber is finely ground hexumite, which is an explosive. They have maybe 20 minutes to get off the planet before it explodes and destroys everything within 10 systems.
Back at the planetary Zaiforge cannon, Keith realizes that Naxzela is a trap for Voltron, and using a Galra fighter, he takes off to attack the Galran fleet, gathering the rebel ships still available along the way.
Lotor is monitoring radio transmissions, and overhears that one of the quadrants is off-limits to all ships. He realizes this is where the battle is occurring and takes off toward it.
Shiro attempts to contact Keith and Coran to warn them away from Naxzela, but cannot break through the shield. Voltron is still trapped on the surface of Naxzela, unable to take off due to gravity, and falls further into the gravity well.
Lance urges Allura to use the same willpower she used to heal the Balmera and to bring the entire team together in order to enable Voltron to escape the planet. "This is your destiny. You are the heart of Voltron," he tells her. She infuses Voltron with her strength of will and they finally lift off, breaking through the shield.
Shiro warns Keith about the planet and the battle cruiser, and sends Coran away as fast as the castle will go. Voltron is flying away from Naxzela as fast as he can.
Keith and the rebels attack the particle barrier around the Galra ship but cannot break through with their energy weapons. Keith realizes this, and sets a route to ram the barrier with his Galra fighter, kamikaze, as Matt yells at him to stop
Just before Keith hits the barrier, the front of the cruiser is pierced by a laser blast - from Lotor's ship - and explodes as the shield disintegrates. Keith manages to pull up in time to miss flying head-on into the explosion, and veers out of the way. Haggar's ritual is broken, and the terraforming machine on Naxzela shuts down.
Haggar and the damaged fleet flee, and Lotor announces to the Paladins and the rebel fighters that he knows they have had differences, but it is time they had a discussion.
"Some of us were asleep during chemistry!"
— Lance to Hunk