Life goes on for Josie, Mae, and Akiko after saving ENIAC and its creators from the Hisser. After finding themselves in San Francisco, they discover a coded message that leads them to the bay where they do battle with a villainous clown known as Side-Splitter. Side-Splitter's power allows him to create numerous copies of himself, so he puts up quite a fight for the three.
After dealing with him, they report to Room 12, where they discover a new villainous plot is underway. Someone's been leaking information to the Japanese Military. If they don't crack the codes and discover Side-Splitter's plot, a lot of innocent people could get hurt. So, the girls offer up their code cracking skills to end this latest attack.
The book was published on August 18th, 2020.
Mask contains examples of:
- Fading Away: The Infinity Trinity take note that this seems to be happening to Hopscotch when they see her.
- They also see the same thing's happening to Mrs. B and Astra. Mrs. B reveals that some unknown force is causing superheroes to fade out of existence, and that the same is happening to them.
- Healing Factor: Josie learns that she has the power to heal herself and others from injury after the Infinity Trinity's first battle with Side-Splitter.
- Monster Clown: The Side-Splitter.
- One-Word Title: Naturally.
- P.O.W. Camp:Near the beginning of the book, Akiko reveals that her whole family was moved to an internment camp along with the rest of the Japanese-American population because of Executive Order 9066. She even takes Josie and Mae there.
- Signature Headgear: The Doll Lady is known in room 12 for wearing a wide hat. It allows the Infinity Trinity to easily identify her on the street.
- Something Only They Would Say: Akiko makes a horrifying realization when she hears Side-Splitter say "even if it's raining gnats and frogs" over the radio. It's her mom's preferred term over "raining cats and dogs". This confirms to her in her mind that her mom is indeed with with The Doll Lady and Side-Splitter.
- Thankfully, this is not the case, as Akiko's mom actually works for Room 12.
- Speaks Fluent Animal: Mae is revealed to have this power. She uses it to great effect by having a bunch of elephants corral Side-Splitter's clown army.
- Street Performer: There are LOADS of these in San Francisco. A lot of them are in Side-Splitter's army.
- Training Montage: Hopscotch and agent Noor Khan are shown training the girls in combat in Room Twelve.