The Genius Club
The Genius Club is a group of students consisting of the smartest students of A Nigma High. They are unofficially led by Irwin Dexter. Besides Irwin, its members are Ruby Kwee, Nadene, the Tech Nerd, and Grayson. Grayson supposedly quits because the blackmailer has told him to, but it turns out he is the blackmailer.
They are introduced in Mastermind. Tina Kwee came to them to question them about Ruby's involvement in The Prank, and the information they provided helped Tina figure out what Ruby was up to.
Later after the bezerk Cleaner incident they move to the new renovated portion of the Library where they hid the headless body of the Cleaner Lee decapitated during the earlier incident, to try to prevent another such incident from happening, but they need the head to figure out how they work.
They ask Lee to get the head while they decipher Radcircles phone for him. After Irwin contributed his help to the deciphering they easily cracked the coding just as Lee got back with the head. With the head in their hands, Irwin finds that there was an extra piece that shouldn't have been there, and that whoever was in control of the Cleaners isn't anymore.