It's Cassie's bright day and Miles needs to get her a present, so he heads to the diamond moon in the galaxy to find the most special moon diamonds to make the sparkliest gift for her after his old gift is smashed.
The episode begins at the Stellosphere where in Miles' bedroom, Miles and his pet robo-ostrich, MERC, are oversleeping when suddenly, Miles' iDisney phone rings out an alarm that woke both of them up! Miles picks up his phone and his face brightens up as he jumps out of his bed shouting "Happy Birthday!" and then crashed onto the floor, face flat. MERC then rolled his eyes and picked up Miles just as he went to his Star Zap to turn it on and look at the pictures of Cassie Starling with dreamy eyes!
Outside the room, Loretta was nearby Miles' bedroom and popped in to see what was going on when she saw that her brother was looking up pictures of Cassie again. Embarrassed, Miles closed his Star Zap and says good morning to Loretta with a nervous smile before he realized that she already knew what he was doing, then sighs heavily. Loretta asks Miles why he was so exciting this morning and Miles explains to her that it's Cassie's bright day, which is her birthday today, and he's prepared a special birthday present for her: a moon diamond necklace with the moon diamonds that he collected from the diamond moon after Gadfly saved him. He puts it in a gift box while Loretta helps him wrap it up and MERC puts a shiny pink bow on top of it.
After having their breakfast and grabbing their star backpacks, Star Zaps, shooting stars, and Wish Pendants, Miles, Loretta, and MERC head outside to find a safe place to take out their shooting stars that will take them to Starland. Miles ran fast and worried that they might be late but while he wasn't looking, he tripped on a root and the gift box shot out of his hands that the moon diamond necklace flew out and landed onto the street, where there was a car that drove by and crushed the moon diamond necklace before Miles, Loretta, and MERC could get it in time!
Miles bent down to pick up the broken pieces and looked down at them in depression as he groaned in frustration, and Loretta and MERC went over to him to see if he was okay, but they can see that he was upset about the necklace. Patting Miles to comfort him, Loretta suggests that they should go to Minnie's Bow-tique to buy a bejeweled bow but Miles told her that he doesn't have that much money to buy a fancy bow for Cassie for that the necklace took him months to make with all his heart, and he can't make another one without another moon diamond. MERC then suggests that they should go to the diamond moon to maybe get another moon diamond and make another necklace, which quickly lifted Miles' spirits up. So in no time at all, the two kids hopped on MERC, put on their space helmets, and flew off to the diamond moon.
In space, Miles flew on his blastboard and Loretta rode on MERC to the moon diamond and they finally arrive there as they landed on the crystallized ground and got to work trying to find the perfect moon diamonds for Cassie's new birthday necklace. Miles picks pink diamonds, Loretta picks magenta diamonds, and MERC picks up white diamonds until all three got every diamond they need to complete the necklace.
Later, Miles sets up everything he needs to make the new necklace. As he got to work, Loretta and MERC watched and were impressed on how Miles made the new necklace with all his heart. After a few minutes, Miles finally finished the necklace and puts it in a new box as Loretta helped him wrap it up and MERC puts the finishing touch on it by putting a bow on top.
- The beginning of this episode is based on the beginning of "The Bubbler" from Miraculous: Tales of Ladybug and Cat Noir.
Miles (Narrating): All That Sparkles.