A refined bookworm determined never to marry; a pugilist and seasoned agent determined to work alone; the case that will test their tenacity.

Penelope Chapman's youngest sister leaves town with a traveling preacher and Penny is sure something is wrong. She goes to the only person she's sure can help her get to the bottom of it?her twin sister, Marianne. She hopes Marianne will convince the Pinkerton Detective Agency to get involved. What she didn't count on was the gruff bare-knuckled fighter that appeared to have more bruises than sense, who is assigned to the case.

Angus Hightower was avoiding the Pinkerton Denver office at all costs since the policy on marrying male agents to the new female agents. He becomes a bare-knuckle fighter for a case until a scandal involving one of their own sends him back to Denver. One look at Penelope Chapman and he dives into the temporary marriage with the intention of solving his case, finding the girl, and impressing his new wife.

Will Penny and Gus find the youngest Chapman girl before it is too late? What happens when they discover that Angus' case and the disappearance of Penny's sister might be tied together, and the danger is more than either of them realized? When Penny goes missing, will Angus be able to save her, or will his love and fists not be enough?