At night, the Ninjalinos return to Night Ninja in the bamboo forest of Mystery Mountain with a bamboo stick after chanting a ninja spell out loud over and over for two hundred nights. The next day, Connor, Amaya, and Greg notice multiple tree branches from Mystery Mountain scattered onto the street. Knowing that something is up, the PJ Masks decide to investigate.
After the transformation sequence and the transport to HQ, the PJ Masks check the PJ Picture Player to see the portal of Mystery Mountain open. Wind is blowing out from it, and on the street, more tree branches are scattered about, along with other objects. The PJ Masks hop on their PJ Rovers and ride off to Mystery Mountain to check out what’s going on.
Halfway up the mountain, Night Ninja is testing out the bamboo stick, which he names the Wand of Storms, for its maximum storm power. The PJ Masks arrive and try to confront him, but he uses the wand on them and blows them away. The PJ Masks are sent to the stairway of the pagoda where An Yu is meditating inside. She comes outside, and the team informs her that Night Ninja is attacking the mountain and that they need her help. They ask if they can come in the pagoda, but An Yu refuses, saying that it is a strict ancient code for only dragon masters to enter the place. However, seeing that the team is in trouble, she lets them go in.
Night Ninja and his Ninjalinos follow from behind and use the Wand of Storms to attack the four kids. In retaliation, the team uses various objects inside the pagoda to barricade the door. A couple of the objects almost gets damaged while doing so, so An Yu sternly steps in and takes care of the barricading. Once the pagoda doors are blocked, she walks up toward a wall of cabinets and takes out a scroll. According to the scroll, to calm down the storm that Night Ninja created, a relic known as the Wind Talisman must be used. However, to obtain it, a true dragon master must complete three tasks.
That being said, An Yu performs the first two tasks without failing. She is tested on her dragon master patience, and then tested on her dragon master determination. The tasks result in a huge dragon statue, and after it is moved to the symbol engraved on one side of the floor, a box comes out from one of the cabinets. An Yu opens it to reveal the Wind Talisman, but when she tries to grab it, it flies over to the ceiling of the pagoda where a cage is located, much to her dismay. She reveals that she did these three tasks before, but while she was able to complete the first two tasks, she couldn’t complete the last one. The reason why is that while she flies up to reach for the cage, it moves out of her reach. She attempts to try the last task again multiple times, but without any success, and sadly flies down to know that she is not yet a true dragon master.
Meanwhile, Night Ninja’s storm is getting stronger. It gets so strong that Night Ninja loses control and cannot stop it, so he and his Ninjalinos take cover. The pagoda starts shaking, and the kids fall down. As they recover, Catboy notices some ancient dragon writing written in the box, saying “the strongest tree has many small branches.” Before the kids can further discuss the riddle, the pagoda doors fly open; Catboy runs over to shut the doors, but An Yu informs him that his powers won’t stop the Storm of the Ninja. Regardless, Gekko and Owlette assist him, and after calling out to An Yu for help, she throws her staff at the doors, and they close, the PJ Masks placing back one of the objects to barricade them.
An Yu is surprised at what just happened: while the Storm of the Ninja is too powerful, the PJ Masks worked together to stop a part of it, with her lending a hand. Suddenly, the kids realize that this is what the riddle in the box was saying, that they should be strong together as they are many branches that make up a strong tree. Taking this into consideration, Catboy uses his Super Cat Stripes to grab the cage while Gekko holds it down using his Super Gekko Muscles. The girls fly up to the cage to see more writing, which are musical notes. Using her Owl Eyes, Owlette sings what is written on the cage while An Yu plays along with her flute. The cage opens up, and the talisman is placed on her staff.
The pagoda doors suddenly fly open again, and sensing the strong winds, the talisman activates and flies over to the source, pulling An Yu and the PJ Masks with it. The staff points up to the sky, and after a few moments, the storm disappears, and everything is calm again. Night Ninja and his Ninjalinos return to the pagoda, mocking them that it is now a mess, but the heroes are not swayed by this and use the talisman to blow Night Night out of the gates. The Ninjalinos help him up and retreat.
An Yu reflects that she was taught to be strong all her life, and after what has happened, she learns that accepting help from others is a sure sign of being a true dragon master, or a great hero. She retrieves the Wand of Storms that Night Ninja dropped to keep in the pagoda for safety and gives the PJ Masks a warm welcome back to the pagoda from time to time. The PJ Masks accept this gesture, and the kids shout out the signature victory phrase.
Work together as a team to accomplish your goals.
This is the thirteenth appearance of Mystery Mountain.