"The Mask" is the seventeenth episode of Season 2 of Teen Titans Go! and the sixty-ninth episode overall. It first aired on 16 October 2014 on Cartoon Network.
Robin's mask doesn't just conceal his secret identity, it hides a terrible secret!
The Teen Titans fight against Punk Rocket, who destroys most of the city with music by using his guitar. When Beast Boy complains that his music is angry, Robin succeeds by making music that is more horrible than Punk Rocket's, but the villain knocks the hero's mask off, losing it in the process. Robin searches everywhere, to no avail. Using the T-Plane, he flies back to Titans Tower, as Raven knocks Punk Rocket unconscious with a single punch.
Robin, crashing into the living room, goes to the bathroom, where he finds behind the mirror a replica of his mask, making the other Titans confused. Robin notices that the other villains of Jump City would destroy the tower if his face was exposed, as to what happened in an episode of the original Teen Titans. Robin walks off, explaining that it won't happen again. The other Titans wonder what is under the mask, so they set out to know what was really under the mask.
Cyborg sneaks into the shower, to the fact that that Robin was using scuba head gear; Starfire heats up Robin's face, to the fact that Robin covered his mask with toast; Raven threatens to take off Robin's mask while he's sleeping, which was revealed to be a bomb, which then explodes (the real Robin was in his closet, sleeping); and Beast Boy tries to take off Robin's mask, to the fact that he wore multiple masks, as Beast Boy removes the masks off Robin's face continuously for days. Robin still refuses to share his secret.
Later, while Robin puts the masks in many boxes, his friends are starting to leave him, noticing that they don't trust him. Robin finally wants the Titans to know his secret. Taking his mask off, he secretly dons a handsome face, to the fact that it attracts his four members. They didn't know that he could hide a face like that, as Robin told them it was a burden. Starfire, Raven, Cyborg, and Beast Boy imagine that they have handsome faces that they could have, but due to them looking currently "hideous", they cry and whimper. Robin notices that it was a reason they didn't want him to show his face; something outside was the other.
Outside, a spaceship appears, and a female alien named Klatak, the queen of the Marshrouvian Empire, who was searching everywhere to find "beautiful creatures". Targeting Robin (who was the one to have the same face as her), she agrees to let him be the king, but he refuses. The Titans fight back, but she is too powerful due to their ugliness. Only Robin can fight Klatak with his face's beauty, as she can't resist its strong power. She and her ship explodes, and Robin explains to the Titans that things like what happened can cause trouble. While the four Titans become depressed that they will miss his beautiful face, Robin hides behind them, revealing what was on his face—his parasitic twin. Robin feeds him a grape as the episode ends.