Sometimes a Rogue (Lost Lords (Putney))

.. Even the most proper young lady yearns for adventure. But when the very well bred Miss Sarah Clarke-Townsend impulsively takes the place of her pregnant twin, it puts her own life at risk. If the kidnappers after her sister discover they've abducted Sarah instead, she will surely pay with her life... A Rogue... Rob Carmichael survived his disastrous family by turning his back on his heritage and becoming a formidable Bow Street Runner with a talent for rescuing damsels in distress. But Sarah is one damsel who is equal to whatever comes. Whether racing across Ireland with her roguish rescuer or throwing herself into his arms, she challenges Rob at every turn.