The Double Deal by William Congreve is a comedy about how the devious Lady Touchwood and her ally Jack Maskwell contrive to break up the marriage of Cynthia Plyant and Mellafont. Maskwell is the double dealer of the title. Lady Touchwood is the passionate and jealous woman that falls in love with her nephew Mellafont. Mellafont is the honest and kind suitor of Cynthia, and Cynthia is a rich heiress in love with Mellafont. The other characters include Lady Touchwood's honest husband Lord Touchwood. Cynthia's stepmother and father Lady Plyant and Sir Paul Plyant, Mellafont's friend Ned Careless, the couple Lord and Lady Froth, the boring Mr. Brisk and the clergyman Reverend Saygrace.

Jack Maskwell is the Machiavellian character the story revolves around. He plans to become heir to Lord Touchwood's fortune and break up the forthcoming marriage between Cynthia and Mellafont so he can marry an heiress. He befriends Cynthia's future husband Mellafont and uses Lady Touchwood love for her nephew to turn Lord Touchwood against her. Only his greed stops him from succeeding.

The other characters are mostly very genuine and just pawns in Maskwell's plan. Even Lady Touchwood, Maskwell's lover and ally, is motivated more by love than greed.