|“||Professor Plum. Polymath. Orphan. Both the smartest and dumbest man in every room.||”|
— Clue #1
Plum was the illegitimate son of Ambassador Peacock, who grew up in an orphanage aided by a regular grant from the Ambassador, much to the distaste of his wife, Mrs. Peacock. Growing up as a gay, Pakistani orphan, he ended up reading everything that he could and eventually came to believe in a deterministic universe, believing that everything was following some kind of cosmic script. After Plum turned 18, the payments from Ambassador Peacock continued to him directly, but after twelve years — after Peacock was murdered — his widow Mrs. Peacock cut off the payments. At some point, Plum met, and began a friendship with, Dr. Orchid.
Ten months after the Ambassador's death, Professor Plum was invited, along with several other guests, to the home of Mr. A. Boddy for a dinner party. Meeting with Dr. Orchid in the foyer of the mansion, he greeted his old friend warmly, but was cut off when he began to speak of their shared history, Orchid not wanting the other guests to overhear. During the dinner, Plum was outraged when Mr. Green threatened Miss Scarlett to prove a point about the relative value of lives; after Mr. Boddy tried to calm things down by having Upton bring mango cheesecake for dessert, the Professor tried to entertain the guests with the "funny story" behind 90% of all mangoes sold in the United States coming from the same source, though Upton didn't find it particularly amusing.
Shortly after dinner, Plum was standing in the mansion's foyer with Orchid, Upton, Colonel Mustard and Senator White, when a gunshot was heard; running upstairs to the house's library, the guests and the butler found Mr. Boddy dead of a gunshot wound, something that was quickly discovered to apparently be the work of Mrs. Peacock. Shortly after the police arrived, Plum spoke to Dr. Orchid about how he had always dreamed of living somewhere like Boddy's mansion; with the two scientists in seclusion together, the Professor asked Orchid whether she "did it".
Soon after Mrs. Peacock was herself killed, Detectives Ochre and Amarillo discovered Mr. Boddy's "blackmail room", containing large amounts of personal information on each of the guests, including Professor Plum; in his case, it included both video footage of Plum in the orphanage as a child, and a ledger detailing the 30 years of payments that had been made to the orphanage and the Professor from Ambassador Peacock, stopping the month after the Ambassador died. The detectives showed Plum the footage of himself as a child; he was unable to give them any insight into why Boddy would have such material, and was angered and upset by what he was shown, and when Upton offered Plum his services, the Professor angrily yelled at the butler to get him something to read.
Deciding to escape from the house and find out why Boddy had so much information about him on file, Plum recruited Dr. Orchid to come with him. The two made their way to the blackmail room, though Plum inadvertently allowed all the other guests to overhear their plan; and when they got there, they were encountered by Detective Ochre, who confronted Plum with the ledger of payments from Ambassador Peacock. Ochre suspected that Plum had killed Mrs. Peacock as revenge, either for keeping him from his father or purely for cutting off his money, which the Professor denied; when Ochre took out his handcuffs to take the two guests back to the interrogation room, Plum knocked him down with a book that he was holding, and the two academics fled out of the window, climbing to the ground via a drainpipe. Orchid and Plum took a moment to regroup in the mansion's greenhouse, but were shocked by what they found in there: a roomful of Surobi Zinnia flowers, thought to be impossible to grow in captivity, and something that — according to Plum — "a lot of people would kill to control".
- Professor Plum originates as one of the playable characters in the original 1949 edition of Cluedo/Clue. His IDW incarnation retains his classic glasses and role as an academic, but lacks the character's signature bow tie and pipe.