The following version of the book was used to create this study guide: Tapper, Jake. The Hellfire Club. Hatchette Book Group, New York, NY, 2018. Kindle AZW file.

Charlie Marder is named to fill a vacant Congressional seat after his predecessor Martin Van Waganan dies of an apparent suicide. Charlie is the son of former Congressman Winston Marder He is married to Margaret, a noted zoologist who is expecting the Marder's first child. Charlie's days are governed by meetings and the strict rules of his office manager Catherine Leopold. While Charlie struggles to find his place in Washington's political scene, Margaret worries about the changes she sees in her marriage – including in how Charlie is reacting to the pressure.

Charlie finds himself drinking far more than he ever had in the past. One night, he falls into a drunken stupor at an exclusive party. When he wakes in the early hours of the next morning, he is in a ditch with a wrecked truck nearby. He has no memories of how he got there and is shocked when lobbyist Davis LaMontagne drives up and discovers the dead body of a waitress who had poured some of Charlie's drinks the previous night. LaMontagne insists on staging the scene, and he drives Charlie home. Charlie is horrified at how quickly he accepts the decision not to go directly to the police.

Within a few days, he confides his situation in one of only two Blacks serving in Congress – Isaiah Street. Street is horrified at Charlie's choices but realizes that Charlie had reacted in the only way he felt would protect Margaret and their unborn child. When Charlie tells Margaret about the wreck, she comes to the conclusion that Charlie has been framed based on her knowledge that Charlie cannot function at all when he is that drunk. She believes it would have been impossible for him to drive a vehicle. Charlie soon learns that there are several secret clubs controlling most of the politics. The Hellfire Club is one, and they are responsible for framing Charlie in order to manipulate his future actions. Another group is controlled by Senator Joe McCarthy in his never-ending quest to find everyone with Communist ties. Just when Charlie thinks he cannot be surprised, he learns that his father and Street are members of a group that reports directly to President Eisenhower. Charlie and Street kill some of the members of the Hellfire Club, including Charlie's office manager Leopold and Congressman Carlin. Charlie is surprised when government officials swoop in and clean up the scene, reporting later that Carlin and several others died in a tragic plane crash. Charlie then kills LaMontagne, ending the immediate threat against the Marders.

Charlie learns that the members of the Hellfire Club are powerful men who lead lives of corruption and debauchery, but they also live by a code that ensures they all protect each other. He knows that the club originated in England with Benjamin Franklin beginning a version of the organization in America. Charlie's knowledge of American history leads him to connect most of the clues in the case with other characters – including Charlie's father – filling in some of the blanks.

Charlie's seat will soon be up for reelection. He considers dropping out of politics to return to the academic world he and Margaret recently left behind. Then, Eisenhower summons Charlie to his office and says he hopes Charlie will become a member of his personal advisory group that includes Charlie's father and Isaiah Street. This invitation paves the way for the second book in the mystery series.