The teammates crew,lover teammates crew, the agent of the R.E.S.C.U.E and the male agent of the R.E.S.C.U.E plan a special birthday celebration for Pan, but when Darlyn and lloyd catches a cold, their element powers put more than just the party at risk.
Darlyn and lloyd is excited because today is pan's birthday and intends to make sure goku's granddaughter's special day is perfect. Using her element powers, she creates a special ice decoration on the top of Pan's birthday cake: figures of darlyn and friends hugging happily together. Zane made a banner that he hung up across the castle courtyard which reads "Happy Birthday Pan". Darlyn and friends spent all morning preparing everything and now time was running out. Before dashing off to wake up Pan, Darlyn and lloyd leaves their friends in charge of looking after everything until the guest of honor arrives.
Darlyn and lloyd tiptoes into Pan's room and gently nudges pan, who is still asleep. Pan struggles to wake up but after being told about the day Darlyn and lloyd has planned for them, she immediately jumps out of bed. When Darlyn and lloyd sneezes, neither of the girl notice that two tiny micegirl and miceboy pop into the air, drop to the floor and scamper away. Starting off the day, Darlyn uses her magic to create sparkly new dresses for each of pan and two friends before heading out on a mystery tour which involves following a long string that Darlyn and lloyd had wound through the castle, leading Pan to different gifts. Inside a suit of armor, Pan finds a bracelet. Inside an armoire, she finds an cuckoo clock. And on a balcony, there's a bouquet of sunflowers. Lloyd sneezes again and more little mice boy and girl pop into the air and tumble to the ground, but still the gangs don't notice. The micepeople scurry into the courtyard where Melody finds them and is thrilled to see them, while kai was scared and jump into pole.
Darlyn,lloyd, pan and two friends follow the string all over Ninjago city. Along the way, Pan discovers more presents: a family portrait, silk stockings, even a fishing pole. All the while, continues to sneeze and each time she does, more little micepeople appear and still the gang don't spot any of them. Pan is having a wonderful time but is concerned for Darlyn and lloyd's health. They feels they should go home and rest but Darlyn and lloyd declines. They leads Pan and friends to Superbeasto and suzi x's party club, where she presents her with one of Superbeasto's beautiful heavy cloaks. Then noticing their sneezing, Superbeasto presents them with a bottle of medicine which Pan accepts gratefully, knowing they may need it. Next, Darlyn and lloyd takes Pan and friends to the center of the village, where a ninjago children's choir sings for Pan.
Back at the courtyard, the other heroes (expect kai, who still in pole) try to keep things under control as more tiny micepeople run in, causing a lot of chaos and trouble for them. When cole spots several little micepeople climbing up to the cake, zane use his snowball power like a bowling ball and takes aim. Snowball rolls into the mice, knocking them away from the cake. Suddenly, the little micepeople knock down the banner. Jay manages to rehang the letters but it isn't quite the same as before.
Meanwhile, Darlyn and lloyd leads Pan to their last stop, where at the top of the clock tower was her last gift. Pan's arms are now overloaded with presents and Their cold is getting worse. Pan insists that Darlyn and lloyd needs to rest, but she doesn't listen. Already the are feeling feverish as they climbs the stairs to the top of the tower till finally they loses their balance. Pandrops her gifts on her friends and rushes to catch her. She notices They are burning up with a fever and needs to get into bed, which Darlyn and lloyd finally agrees to. As Pan escorts them hosptial, Darlyn and lloyd feels they ruined their perfect birthday but Pan tells her she hasn't. Then as they enter the castle gates, Pan is surprised by the heroes and the hundreds of little micepeople who present her with her birthday cake and a special birthday song. Caught up in the excitement of the song, emmet sings loudest of all and bursts out "I love you, Baby!", becoming very embarrassed with Pan grinning at him happily. Though tired, Darlyn and lloyd insists on blowing the Birthday Horn, and sneezes into it, launching a giant snowball all the way to the prison island, where it hits Dr. Phineus Phibes as he is shoveling manure at the royal stables.
Afterwards, Wu and garmadon helps Darlyn and lloyd into bed and thanks pan for a great birthday and giving her the best present she could ever have; Darlyn and lloyd letting her take care of her. High on the Grimsborough city where stands Jones's house, Jones is visited by teammates crew who present to them a parade of the little micepeople who would now be living with them, while kai goes down and out of zane the special end with micegirl appears scare him to screams.