The Very Debonair Lady Claire

When Claire Barton's twin is murdered, she takes his place as a code breaker for the War Department to flush out his killer. Her ruse works perfectly--until the man who once broke her heart becomes her new spymaster. He sees right through her disguise but if he thinks he can stop her from doing what she must, he's in for a bigger surprise than when he'd realized just who wore the trousers now.
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The last thing Lord Andrew Sedgewick expects to find when he's asked to root out a traitor is the ...