The season one finale of Moon Girl and Devil Dinosaur begins with Lunella Lafayette at an all-time low. In the previous episode, she is pursued by the Enclave for her portal generator and discovers that her grandmother Mimi used to work for them as the original Moon Girl. The Enclave’s leader, Maris Morlak, captures Mimi and destroys Lunella’s hidden lab and her Moon Girl gear, with her pet dinosaur Devil seemingly trapped inside.
That’s a lot for a 13-year-old girl to go through in just one episode, but all hope is not lost. Devil is still alive and with Lunella’s best friend and manager, Casey Calderon. After catching Casey up on everything she missed, Devil takes the girls back to Casey’s apartment to regroup.
What should they do now? Calling S.H.I.E.L.D. is out of the question. Unfortunately, Lunella has the bright idea to share Agent Maria Hill’s phone number with Casey, who quickly rises to the top of Hill’s “Do not call me” list. Despite their lack of resources, the trio is able to figure out where the Enclave base is: North Brother Island. Before they leave, Casey gives Lunella a new sequined stealth suit that will make her invisible after her old suit was destroyed.
Once they arrive outside the Enclave’s base, Devil and Casey attract the attention of the guards while Lunella sneaks inside the abandoned mansion. Devil wastes no time beating down the guards in revenge for their last fight, with Casey putting her newfound Bo staff skills to good use (her temporary stint as Moon Girl must have inspired her). Meanwhile, Mimi is building a new portal generator while trying to appeal to what’s left of Morlak’s conscience. She warns him of how dangerous the generator is, but he refuses to listen. All he cares about is being recognized for his work.
Lunella slips in after Maris leaves to rescue Mimi, but she reminds her granddaughter that the Enclave found her before and can do it again. Mimi also confirms something that was alluded to back in the pilot episode — that she knows Lunella is Moon Girl this entire time and even cleans the lab and washes her suit to help out. Lunella points out all Mimi has done for her family, triggering a flashback to how Mimi became a Lafayette. She literally crashes into Pops as he hands out “help wanted” fliers for his roller rink. She takes the job, and it isn’t long until she and Pops fall in love and marry each other. It’s one of the most heart-warming scenes of season one — watching how supportive their relationship is as their family expands when they have their son James, followed by the arrival of his wife Adria and their daughter Lunella. Mimi explains that she never feels burdened because the Lafayette family is always there for her when she needs them.
Unfortunately, Maris the mood killer returns and activates the portal, summoning three giant creatures he can control with a whistle. Lunella and Mimi are able to defeat the monsters with help from Casey and Devil, sending them through three separate portals. Maris refuses to give up and tries to override the generator. Instead, he opens a portal that sucks in everything in its path, including him! Pitying her former partner, Mimi tries to rescue Maris, only to watch him be sucked through the portal. Lunella finds two switches that will close the portal, but Mimi realizes that somebody has to be on the other side of the portal. Lunella tells Mimi she loves her as she allows herself to be sucked through the portal while she and Mimi push their respective buttons.
With the portal closed for good, Mimi grabs some equipment and starts working on the generator, all while vowing to bring Lunella back. The post-credits scene shows a close-up of Lunella’s eyes opening as she wakes up on the other side of the portal. “Where am I?” Lunella wonders as the screen fades to black.