The Highlander’s Unexpected Wife by Tarah Scott

She intended to stop a scandal…not become one.
Lady Alison has a penchant for mischief. How else could she end up in the bedchamber of the notorious rake Viscount Weston? She expected to rescue her foolish cousin, instead she finds herself engaged…and embroiled in the devious exploits of sex slave traders.
Cameron Hunter, Viscount Weston’s business dealings require discretion. The last thing he needs is a mischievous wife. However, Lady Alison might be the perfect distraction. A wife as opposed to marriage as he is.
Dangerous games are afoot. Now assumptions have Alison in the hands of the enemy. Cameron must keep his secrets, rescue his betrothed, and convince her he isn’t the man she believes him to be.