Elon O'Connor, boy genius, tests out the Eco Team's new jet prototype when things take a turn for the worse; Sigma Corp. announces their latest earth-destroying venture; a surprise from Elon's long-lost grandfather hides in plain sight.

The first of Theodore's adventures is revealed, along with the identity of his research partner; Harrison and the others strategize to fight Sigma Corp.; separated from the others, Elon discovers a lone otherworldly being.

Fascinated by his abilities, Elon tries to persuade Leo to stay by his side; Leonard, the director of Sigma Corp., detects a strange energy signature and launches a new mission; Elon faces the ultimate test of smarts and strength.

Elon enters an illusory realm to take a special test in hopes of becoming an Infinite Warrior ally, but the challenges only increase; when the Raven finally unveils Elon's results, Leo must make a decision that will decide the planet's fate.

Elon and Leo team up to defend the earth and the Archean Stones from Sigma, but before they launch a mission, they must throw off Elon's parents; Harrison shares exciting news, and a breakthrough takes the Eco Team in a surprising direction.

Elon and the Eco Team fly to England as part of their environmental awareness tour, but Elon has an ulterior motive; with Sigma nearby, a showdown pits these foes against one another; someone from Leo's past lurks in the shadows.