When the Fangpyre invade Ed & Edna's Scrap N Junk to use the scrap to make vehicles, some snakes bite an old helicopter, turning it into the rattlecopter. When the Ninja arrive the next day, the Fangpyre escape after the battle, with Fangtom and Lloyd riding on a platform dangling from the rattlecopter. However, Jay pursues the copter in his new Storm Fighter and manages to steal the Fangpyre Staff. Nya later drops it though, and the rattlecopter flies down to the ground for Fangtom to retrieve it.
The Fangpyre ride their vehicles, including the rattlecopter, into battle against the Hypnobrai tribe in the Glacier Barrens. However, Fangtom and Skales team up and betray Lloyd. The latter tries to regain control by climbing on top of a rattlecopter to bark orders, but the biomechanical vehicle notices him and swings its tail back to throw Lloyd off.
Pythor jumps onto the rattlecopter platform to make an escape after stealing the four silver fang blades from the Ninja. Noticing that the rattlecopter won't make it to Ouroboros in time, Skales tells Pythor about their plan to get to the city faster, the Serpentine Train.
In the Lost City of Ouroboros, Lasha and Lizaru are fighting in the Slither Pit arena. The fight is interrupted when a Rattlecopter lands in the arena, prompting Chokun to set up a red carpet with a seat and an umbrella for Lord Garmadon. The four-armed villain informs the Serpentine Generals that he has an ingenious plan, saying that Captain Soto's journal mentions a fabled island known as the Island of Darkness. Skales is skeptical, but the Generals leave with Lord Garmadon in the Rattlecopter.
While Lord Garmadon and the Serpentine Generals ride in the Rattlecopter, Lord Garmadon complains about being unable to find the island, and he orders Snike to turn the Rattlecopter around. Skales lies to Lord Garmadon by saying he has spotted the island, but once Lord Garmadon looks, Skales shoves him into the sea below. The Generals then declare Skales the new Snake King.