She scored him zero on her marriage assessment. Fate had other calculations in mind.

Miss Abigail Sears, American heiress and devoted scientist, has created the perfect formula for matrimony—her meticulously designed "Husband Compatibility Assessment." With her stepfather's ultimatum hanging over her head like a guillotine, she has until season's end to secure a husband of her choosing before he selects one for her.

When Abby witnesses Viscount Julian Lockhart in a dawn duel, he fails her assessment spectacularly. Dueling tendencies? Automatic disqualification.

"Passion cannot be quantified, Miss Sears," Julian murmured, his gaze holding hers with maddening confidence across the dinner table.

"Everything can be quantified, my lord," she countered. "Even your spectacular unsuitability as a husband."

But the carefully controlled experiment of the Rothbury Abbey house party yields unexpected results when a violent storm strands them overnight in a hunting cottage. Scandal erupts, a hasty marriage is demanded, and Abby makes the shocking choice to refuse—even at the cost of her reputation.

With London society turning its back on her and passage booked to America, Abby believes her scientific approach has failed her completely. Meanwhile, Julian, who never intended to marry at all, discovers that the one woman who refuses him might be the only one he cannot live without.

For a woman determined to marry by science and a man who scorned the very idea of matrimony, their greatest discovery may be that love follows no formula at all.