Determined to escape marriage to her fortune-hunting guardian's idiotic son, Caroline Trent runs away and winds up in the arms of Blake Ravenscroft, an agent of the crown who mistakes her for a notorious spy and takes her captive.
When Elizabeth Hotchkiss, a poverty-stricken companion, stumbles upon the book "How to Marry a Marquis" in her employer's library, she decides to use its guidance to find a husband to support her siblings.