Kane and Abel by Jeffrey Archer follows the lives of two boys, born on the same day to very different circumstances. Baby Wladek is born in a forest in Poland, found shortly after his mother died giving birth to him. A young hunter finds the baby and takes him home, making nine mouths to feed in the poverty stricken home. On the same day in Boston, William Lowell Kane is born to a banker and his wife with all the conveniences a 1906 hospital has to offer. Upon taking the baby home, there are nine people in the Kane household, if you count the servants.

A good education is destined to be part of William's future. Shortly after his birth, his father enrolls him in a prestigious private school. Wladek's educational opportunity comes by sheer luck. Word of his intelligence makes its way around the Polish countryside, and a Baron seeks him for a playmate and classmate to be tutored privately in his castle with his own son, Leon. Young Wladek will not go alone and asks to take his older foster sister Florentyna with him.

Both young boys deal with tragedies that children should not have to endure. William's father went down with the Titanic. William and his mother would have been on the ship with him if William hadn't gotten sick on their trip to England. The mother and son stayed behind until it was safe for the sick boy to travel. They learned of Mr. Kane's death in newspaper headlines.

Wladek's best friend Leon is killed when Germans take over the Baron's castle. Wladek, the Baron and Florentyna are held among other prisoners in the dungeons of their own homes. Wladek, who had played hide and seek in the dungeons, knows them inside and out and takes control of the prisoners to make sure they all sleep and eat each day. Shortly before the Baron dies in captivity, he bestows his silver bracelet upon Wladek and gives him the castle. Upon his death, Wladek learns that he, too, is the Baron's biological son, for they share a similar birth defect. The Russians take over the castle and take the prisoners to a concentration camp. Wladek is eventually able to escape, also striving to make his father proud and to take back the castle that is rightfully his.

When Wladek starts his new life in America, he adopts the name Abel Rosnovski. He and William Kane cross paths several times throughout their lives and find themselves as arch nemeses with a little too much in common.