While making repairs to the castle, the Paladins encounter unusual spongy spores that lead them to a planet of brilliant engineers- the Olkari. When landing, Team Voltron meet the Olkari people in the forest, where they adapted from machine to nature based technologies. When rescuing the Olkarian king Lubos, Team Voltron find he willingly sold out his people as slaves to live in comfort, as he builds a super-weapon for Zarkon's forces. As Voltron engages the super-weapon, it learns and adapts to their attacks, even replicating them. After Pidge has help from the Olkari, she reconnects to her Green Lion in a way that allows her to summon a new weapon, which when the Black Cubes attempt to clone, instead grow massive plant roots. When leaving Olkarian space, the Castle of Lions is intercepted by a Galra war fleet.
For millennia, the evil Galra Empire has plagued the universe by conquering planets and destroying their inhabitants. The only known threat to the empire's power and plans, is the legendary "Defender of the Universe" Voltron, a 100 meter tall robot warrior composed of five lion mechas whose whereabouts are presumed to be unknown. The Galra Empire's path of conquest and search for Voltron has led them to Earth's solar system. A group of space pilots-Shiro, Keith, Lance, Pidge, and Hunk-discover the blue lion and immediately get swept up into the Galran War. They meet Princess Allura, become the next Paladins, and reunite the five lions to form Voltron and free the universe from the Galra Empire.
**NOTE: Even though Netflix releases all episodes of Voltron: Legendary Defender on one day, they are portrayed on the TV Calendar as airing one episode a day, for ease of visualisation.
Voltron: Legendary Defender - Greening the Cube Synopsis and Schedule