What's the first name of the person whose plan Sebastian decides to get on board with?
In an upscale New York City mansion, wealthy and popular teenager Kathryn Merteuil is discussing her prep school with Mrs. Caldwell and Mrs. Caldwell's daughter, Cecile. Kathryn promises Mrs. Caldwell that she will look out for the naive Cecile. Kathryn's stepbrother, Sebastian Valmont, enters the room, whereupon Mrs. Caldwell reacts to him coldly and leaves with Cecile. 
Kathryn reveals to Sebastian that her real intention is to use Cecile to take revenge on her ex-lover Court Reynolds, who dumped her for Cecile. Kathryn asks Sebastian to seduce Cecile, thereby rendering her a "tramp" and spoiling her in Court's eyes.  Sebastian refuses as he is planning to seduce Annette Hargrove, the virgin daughter of their prep school's new headmaster who published an essay in support of chastity until marriage.
After some negotiation, the two step-siblings agree on a wager: If Sebastian fails to bed Annette, Kathryn gets Sebastian's vintage Jaguar XK140; if he succeeds, Kathryn will have sex with him, as Kathryn is the one girl Sebastian has failed to bed. 
Sebastian's first attempt to seduce Annette fails, as she had already been told of his bad reputation. He vents to his gay friend, Blaine Tuttle, who suggests that the informant might be Annette's ex-boyfriend and closeted jock, Greg McConnell. Sebastian bribes Blaine to seduce Greg, while secretly filming their meeting. Sebastian then threatens Greg with the photographs, but the latter denies warning Annette. Greg is then ordered by Sebastian into both identifying the true informant, and presenting Sebastian in a good light to Annette. Later, while gushing about Sebastian to Annette, Greg discovers that the culprit is Cecile's mother, Mrs. Caldwell. Wanting revenge on the Caldwells, Sebastian finally agrees to corrupt Cecile.
Kathryn