His 24-Hour Wife is the third book in The Hawke Brothers. They are:
What happened in Vegas didn’t stay there for CEO Adam Hawke and go-getter Callie Mitchell. And their drunken lark of a wedding is coming back to haunt them. Because Adam and Callie are now working together, and she’s being blackmailed over their very personal connection by a coworker. To deflect the threat, Callie and Adam make their sham marriage look real. But the passion that ensues is no sham. Could their wedding lark have real wings after all?