After getting the Scythe of Quakes, the Ninja set out to find the next three Golden Weapons. Traveling by boat, the Ninja set off to retrieve the next weapon, the Shurikens of Ice. While on the boat, Sensei tells the four about the Tornado of Creation and what it is capable of doing. When they reach the Frozen Wasteland, Zane attempts to grab the Shurikens, freezing him in a block of ice in the process. The Guardian of the weapon, the Ice Dragon, is awakened, and the other three Ninja lift Zane up and ride atop him out of the Frozen Wastelands to the boat. They hit a pillar on the way out, breaking Zane out of the ice.
Their next stop is the Floating Ruins, where the Nunchucks of Lightning are being kept. When Jay grabs the Nunchucks, the Lightning Dragon appears in a flash. Using Jay's gliders, they escape to the Forest of Tranquility. Sleeping in the Forest, Kai wakes up to see Nya standing nearby and calling his name. She runs to the Fire Temple, Kai running after her. When he arrives at the Temple, he finds the Sword of Fire, the last Golden Weapon needed. While he is going up to Nya, she reveals herself to be the shadow of Lord Garmadon. Then the real Nya is dropped down on a chain, dangling over the lava. To save her, Kai grabs the Golden Weapon, and once Nya is on solid ground, Lord Garmadon summons Shadows of the Red Ninja to claim the Sword of Fire. Unable to strike the rapidly-multiplying Shadows, Kai is quickly defeated, but Sensei Wu comes to his rescue, using his own shadow to fight off the doppelgangers.
Meanwhile, Cole, Jay, and Zane are all captured by the Skulkin, who steal the three Golden Weapons in their possession. The Ninja soon escape, using a sword Jay stole from Nuckal, and engage the Skulkin in an attempt to reclaim their weapons, but the villains manage to escape to the Underworld.
Back at the Fire Temple, Garmadon awakens the Fire Dragon to prevent the group from leaving. Sensei Wu can think of only one way to stop Lord Garmadon: going into the Underworld to fight him directly. Taking the Sword of Fire with him, the old master sails down a river of lava, leaving Kai and Nya to face the Dragon alone.
While Garmadon is not called the King of Shadows in the episode itself, he would eventually be referred to this way in Dread on Arrival by Harumi eight seasons later.
The episode title refers to Lord Garmadon, who appears as a red-eyed shadow in the mortal realm and summons the shadow warriors to take the Sword of Fire from Kai.
Some airings of this episode place it and Weapons of Destiny together as a single episode, due to the combined time length being 20 minutes, the normal length of an episode.
Wu seems to create a tea cup out of thin air when explaining the Tornado of Creation. However, according to Tommy Andreasen, this was not a use of the power of Creation and was simply "A trick to get his point across".
When the ninja arrive at the Frozen Wasteland, Jay is wearing his DX outfit.
It is physically impossible for Wu to create the shadow of an eagle with his hands.
This may have been an intentional exaggeration for effect.
When the Fire Dragon appears in front of Wu, Kai, and Nya, Wu's mustache has an unnatural shape.