Jack is a young man of medium size in his early thirties, with wavy dirty blonde hair, stubble and blue eyes. He wears a loosely buttoned red shirt (described as frayed in the novels) with the sleeves rolled up and a couple of necklaces visible round his collar. He wears dark trousers and has a bangle around his wrist. His accessories are mentioned to be valuable and not suited to his appearance.
Jack has a carefree and lazy personality, living a carefree life. He is also plagued by survivor's guilt following his climatic legendary gambling duel against King which puts him into a depressed rut. later, after finding absolution in saving King's daughter, Jack's life takes a turn for the better and he becomes much happier. Jack is a very calculating and an insightful gambler. he reads situations and people to come to a truth, often going deep to the core of a person to find out how best to use a situation. He is not afraid of going for the big plays, even at extreme risk to his own person.
Jack used to work for a man named 'Enrique' who jack would win card games for in the criminal underworld. Jack admired Jack, who was a master of his craft. Jack aspired to be like him and worked hard to hone his skills until he was a gambler of equal reputation. Seven years before the events of Gambler Jack, Jack duelled King in a card game and won, with the latter forfeiting his life as it was a game used by various criminal games to determine the outcome of a struggle for power.
Jack spends his introduction winning games in a seedy Calvardian bar on the Northern outskirts of town, while also drinking, fighting and spending his days in idle recreation. the entry of a mysterious girl, Halle upsets the equilibrium of the room when she challenge him to Poker and starts to win, beating Jack. She introduces herself as the daughter of King, the man Jack killed. He invites her to take a shot at his heart with her latest model Orbal Gun. She doesn't take the shot, saying it would be meaningless here, inviting him to the Harbor. She hands him a card with the signature 'Enrique' - a name familiar to Jack.
Jack travels to the harbour and boards the very same ship he duelled King on all those year ago. Many of the underworld had gathered to watch the game, including Chief Minister Shamrock, dubbed the 'Monster of the Underworld' who was the host. in a territorial dispute, Enrique would this time be betting on Halle, with his rival, Won, having Jack instead. At the stroke of midnight, the game commenced.
Jack never spoke to Halle during the games, even with the latter constantly talking, trying to put him off his game. Until, Jack began a story about his past with King and how they were paired off against each other, just as Halle seemingly takes an advantage. Jack reveals he never truly won, and King lost in order to protect his family. Enrique tries to intervene and stop the truth getting out, but Won signals his men to stop any interference. Jack pulls four Kings and beats Halle's four Jacks. Jack had apparently cheated and swapped the hands, but that was okay as long as it couldn't be proven. It was the same trick king used to throw his original match. Jack reveals Halle had been poisoned and the antidote would only be given if he lost.
Jack claims Halle as his prize, saving her life from shamed Enrique. He saves her as part of his debt to king and gradually improves his life from then onwards. Halle later turns up at the bar and challenges him to a game- on friendly terms.
Jack is the star of the Fourth Sun Door, named The Casino -Gambler Jack-, where the player challenges him and Halle to a game of Blackjack or Poker. The game briefly mentions his background from the book, and the patrons of the bar where this take place are enthused about the prospect of Jack taking a match seriously.
Months later after Gambler Jack, Jack and Halle live in relative happiness and they go to a nearby town with a movie theatre. Jack falls asleep during the movie and is chided by Halle. They then meet the very same actress from the movie they just watched, the attractive Nike and old acquaintance of Jack's, Leonard, another disciple of King. Jack is invited to go to a race track with Leonard where they have a race. Jack holds back and is noticed as doing so. Leonard asks him why he held back again. Jack had simply not wanted to embarrass Leonard in front of Nike, and was ashamed that king had always favoured him over Leonard.
Back at the bar, where Halle is the new top dog, Nike shows up. Nike wins against Halle, apparently by cheating but as it can't be proven, it stands. Halle is then kidnapped and Jack given a challenge to get her back. Jack travels to one of Calvard's most known race tracks where it turns out Leonard is behind it. Leonard wants the necklace of Halle's that was given to her by her father King. It has huge amounts of data on the criminal underworld that Leonard wants to use to move up the ranks of politics.
To get Halle back, Jack must defeat Leonard in a game of bets on the car races, which Leonard seemingly wins steadily, but jack takes it at the last moment by placing an extremely unlikely bet and bribing the driver, after sensing the driver wanted an out from the world of underworld betting. Jack provided him with an out.
Nike reveals herself as a Rocksmith Agent and arrests Leonard. The prize money is seized and Jack and Halle return to the bar. Jack reveals the code to the pendant drive, which is used by the authorities. Nike one day returns and proposes working as team once again.