Gene and Natalie are always making friendly bets, and the most recent one had sexual stakes. Taking a cue from that, Natalie tries for something she's always wanted to do with him - but she'll have to bet her own bottom for the chance.
The story describes the accounts of Tom after his discovery of a drug that emulates the response of the female brain to ovulation and enhances it 1000x.
It makes women horny beyond control, releases eggs, makes them pregnant even if on hormonal birth control, numbs the gag reflex and pain of deflowering, among other things.
Tom discovers slowly how to use this drug to make a living, entertain a growing harem, cuckold, and ultimately spread his genes around the world.