An Indian nun and an English doctor have conjoined twin babies in Ethiopia. (Yeah, you read that right: a nun and doctor had a kid.) The mother, Sister Mary Joseph Praise, dies in childbirth, and the father, Dr. Thomas Stone, flees the scene. The babies, Marion and Shiva Stone, are raised by Hema and Ghosh, the doctors at the hospital, and grow up to be doctors themselves.
After they're un-conjoined, that is.
Their childhood is shared with their friend Genet, the maid's daughter, with whom Marion falls in love. Can't resist the girl-next-door thing, we guess. Marion wants to have sex with Genet, but he wants to wait until they're married. Well, Genet can't wait, so she does it with Marion's twin brother, Shiva. Six of one, half-dozen of the other, right?
Wrong. The betrayal ruins all of the relationships.
So Marion goes to medical school, Shiva works as a doctor without formal training, and Genet becomes a revolutionary. She gets Marion into trouble, and he has to leave the country. He goes to New York and finishes up his education there, finally becoming a surgeon.
In the U.S., Marion meets Dr. Thomas Stone for the first time, who is himself a world-famous liver transplant doctor. He also runs into Genet, who comes to his house sicker than a dog and asking for his forgiveness. Marion finally has sex with Genet, after wanting to for many years, but it's obviously very unpleasant for her: she's totally sick, and she bleeds and urinates during the whole painful ordeal.
Genet disappears again, and Marion gets really sick. It turns out that he's caught hepatitis B from Genet, who had been in jail. He's taken to the hospital and slips into a coma. Dr. Stone sends for Hema and Shiva, who come to take care of Marion.
Shiva volunteers to give part of his liver to his brother in an experimental surgery. They go through with it and everything goes without a hitch. Unfortunately, some of the medicine that Shiva takes causes a clot in his head—probably in the spot where he and Marion were joined in the womb—to come loose, and it kills him.
Marion goes back to Ethiopia with Hema and lives there for the rest of his life, practicing medicine and building up the hospital where he grew up.