Donny Lindstrom married Vickie Moore only months after meeting her. Now he knows what others were trying to warn him about: his wife was becoming harder to deal with than their young daughter. The only ones who truly realize how messed up his marriage has become are his in-laws: Tracy and Micah McKinley. Tracy considers her marriage a happy one for years, until the day her husband comes home and shatters everything she thought was true with his latest revelation. Suddenly, she can’t be married at all, and there is no one left for her to rely on except Donny.

Tracy and Donny are good friends, who share nieces, Saturday night barbecues, holidays, and kids’ sports games. They are not, and have never, considered each other anything more than amicable in-laws. Donny is the fill-in brother she usually calls if she needs help with something, and Tracy’s the nice aunt he relies on to babysit his young daughter.

Micah’s shocking betrayal soon leads him to beg Donny to watch out for his wife and kids after he leaves. Donny agrees, but doesn’t, not even for a second, think that request will turn his already tumultuous life upside-down. However, everything soon changes when Donny begins to see a different woman in Tracy than he’s ever known, and wonders if he is indeed married to not only the wrong woman, but also the wrong sister.