The Cluemaster is a Gotham criminal who tried to get a fighting advantage by figuring out Batman's secret identity. In many of his early crimes he became known for leavening elaborate clues behind. This of course never goes well. He ends up making friends with other villains like Clock King, Big Sir, Multi-Man, and Major Disaster. They all band together to become the Injustice League. This league does not last long before they decide to give up a life of crime. The five of them try to reform themselves with the help of the Justice League. They are given a remote base of operations in Antarctica. G'nort is also sent there to keep an eye on them, or at least that's what the Justice League told G'nort.
Cluemaster vs Riddler
In Detective Comics #705- 707, the Riddler sends his henchwomen Query and Echo to release the Cluemaster out of prison. The escape attempt is a success although the Cluemaster was against the idea. Meanwhile, the Riddler, who has a broken arm injury (Which he inflicted to himself deliberately), makes his own daring escape out of the hospital.
The Riddler unites with the Cluemaster in his hideout. It seems that the Riddler and the Cluemaster had some rivalry in the past and the Cluemaster fears that the Riddler might want to kill him. Fortunately, the Riddler never sees him as a competition but he still wants to get rid of him anyway just to gain monopoly in the world of puzzles. Soon after, Batman and Robin finds the Cluemaster on the streets who is rigged with twenty pounds of semtex plastic explosives. The bomb is remote controlled and would detonate if the Cluemaster (Against his will) will not follow The Riddler's instructions. With an ear piece, The Riddler sends cryptic clues to the Cluemaster which he has to guide Batman in to different directions. This is to keep Batman and Robin misinformed while the Riddler, Query and Echo made an attempt to steal valuable merchandises at a baseball store. However, the Riddler''s attempt to mislead Batman foils and is confronted by the Dark Knight once again. Batman knocks the puzzle trio out cold and send them back to prison along with the Cluemaster.
After things fell apart with the league and many of his friends were left dead, Cluemaster ends up going back to his life of crime. With one exception he decides it is no longer a good idea to leave clues behind. This also fails and he's sent back to prison were he is asked along with his friends to go on a suicide mission for a full pardon. Cluemaster accepts for more than just that reason. He also wants to make his daughter Stephanie proud of him. The mission goes very bad leaving Big Sir, and Clock King dead. Cluemaster is also seriously hurt. He goes through rehabilitation in hopes of reuniting with his daughter only to find out she has been killed.
His daughter was Stephanie Brown, a.k.a. the superhero Spoiler. She started crime fighting to get back at her dad for all the years he ignored her. She even helped capture her father. After this she decides that she likes crime fighting and even briefly takes over as Robin. This is what leads to her death.
Now Cluemaster has an all new reason to hate Batman. He changes his name to Aaron Black and is attempting to take on Batman. After all this is not the first child to die working for Batman. Some time after it's revealed that Leslie Thompkins faked Stephanie's death and switched her body with another blonde woman, Stephanie becomes the third Batgirl and Arthur leaves her clues leading to his prison cell. Arthur poisons Stephanie with a Black Mercy and says that he plans to make up for lost time and wants to "make you [Stephanie] a better Batgirl", presumably so she won't be in such a dire situation or so severely injured again.
Cluemaster's plan was to kill the Batman with a gun. Apropos because his parents dies the same way by a criminal of no major consequence. As he is about to pull the trigger his throat is cut from behind by Lincoln March.
Suicide Squad: Most Wanted
Cluemaster is seen alive once again. He has a run-in with Catwoman and El Diablo (Santana). He has them leave his apartment by handling Apokoliptian Tech.
Cluemaster is incarcerated during Flashpoint. While on death row, it is shown that he was secretly smuggling Plastic Man inside his body. Plastic Man breaks out of Cluemaster's body to free Heat Wave from prison.
Powers and Abilities
Cluemaster has a lot of gadgets including plasti-glass pellets attached to the front of his uniform. The pellets contain offensive weaponry including: blinding incendiary flares, smoke, incapacitating gas and explosives. He also has above average intelligence and is fairly adaptive.
In other media
A radically different version of the Cluemaster appears in the animated series "The Batman", voiced by Glenn Shadix as an adult and Kath Soucie as a child. He first appears in the episode "Q & A", in which he is an insane, obese genius who sought revenge on the people he blames for rigging his last question on Think Thank Thunk, a game show on which he competed when he was a child (when he lost on the show, he was awarded with a lifetime's supply of jelly-filled snack cakes as a second-place prize, which he obsessively gorged himself on, leading to his hideous obesity). In his debut episode, Cluemaster attempts to take his revenge on the show's producer, host, and the contestant who had beaten him. After humiliating them in public and kidnapping them with a squad of dwarf minions, he places them on a patently unfair parody of Think Thank Thunk, where if they fail to ask him a question he can't answer means death in a large tub of acid. Cluemaster managed to answer many seemingly impossible questions, including naming all of Jason's Argonauts and a thousand places of Pi, before Batman arrived at his hideout, which was his elderly mother's basement. Playing "all or nothing", Batman stumps the Cluemaster with the one question he does not know: the identity of the Batman. Throwing a temper tantrum, the Cluemaster attempts to unmask him, but is defeated and taken to Arkham Asylum. Cluemaster later appears in the episode "Rumors", as a captive of the title character, a ruthless vigilante based on Hush, along with the bulk of Gotham's master criminals. At the episode's end, Batman frees Cluemaster from his imprisonment by Rumor . The captured criminals then attack Batman and Cluemaster was accidentally frozen by Mr. Freeze.
Batman: The Brave and the Bold
Cluemaster appearance in the Batman: The Brave and the Bold episode "A Bat Divided!", playing billiards with Tiger Shark, Catman and the Spinner at the "8 Bar", a known haunt for third-rate costumed villains. The bar was soon crashed by three atomic counterparts of Batman, each seeking action. Cluemaster vaulted onto the billiard table to seize the Batman counterpart and was badly beaten, staying down for the rest of the fight. He later makes a cameo in "Joker: The Vile and the Villainous" where he was seen at the bar where the bad guys hang out.