For a book like this, I'd say you're wasting time reading reviews, because please just get hold of a copy and read it yourself. Not because of its length - my paperback copy numbers it at 347 pages - but because it's so easy to read, so fun, that you're either going to finish it in no time, or you'll not finish it at all.
The story began with Justin Alastair, the Duke of Avon, buying a child from the gutter because of the boy's resemblance to his nemesis, the Comte de Saint-Vire. Titian hair paired with black eyebrows was an unusual combination indeed, and he strongly suspected that in the child, he may have found the means for his revenge at last - a revenge that has been brewing for two decades, because he wished to ruin his enemy thoroughly, and in the most bloodthirsty way possible.
So he took the boy home and made the boy his page, to the astonishment of his guest, Hugh Davenant.
It was no secret that Léon/Léonie was actually a girl in disguise, dressed up as a boy by her foster brother. A delightful character, once she got over her shyness. She was also, as it turned out, a rather violent young lady:
- “I tried to kill her once,” said Léon naïvely. “With the big carving-knife.”
“Her hatred is not incomprehensible,” said Justin dryly.
- “I should like people to fight over me,” Léonie said. “With swords.”
He flaunted her in Paris, and attracted no little attention.
“Saint-Vire was admiring your page, Justin,” Davenant said. “He is exciting no little attention.”
“No doubt.” Avon snapped his fingers imperiously, and Léon came forward. “He is almost unique, my dear Comte. Pray look your fill.”
Throughout the tale, Avon continually sought for evidence to destroy his enemy, while the Comte de Saint-Vire endeavoured, repeatedly, to remove the most discriminating evidence - Léonie herself - from Avon's clutches. This was made more difficult for him when Avon decided it was time for Léon to be a lady again, and adopted her as his ward. It was a game they played, in which Léonie was both a weapon and a jewel, culminating with a satisfying final showdown between the two enemies.
“When last I saw Léonie—Léon she was then—it was ‘Yes, Monseigneur’ and ‘No, Monseigneur.’ Now it is ‘Monseigneur, you must do this’ and ‘Monseigneur, I want that!’ She twists him round her little finger, and, by Gad, he likes it!”
Alastair/Léonie's relationship was delightful to read. Heyer did not play coy, there was no love triangle. The main issue was their significant age difference; at nineteen, she was half his age.
“She is twenty years behind him!”
“Do you think it signifies? I would not give Justin a bride his own age. I’d give him this babe who must be cherished and guarded. And I’ll swear he’d guard her well!”
True to the case, His Grace of Avon found that he had forgotten his old quarrel with the Comte. He still sought revenge, but for what the heroine has suffer in her childhood due to her father's abandonment, than for himself.
And I leave you with this:
“Léonie, you will do well to consider. You are not the first woman in my life.”
She smiled through her tears.
“Monseigneur, I would so much rather be the last woman than the first,” she said.