It’s been five years since Allison Montgomery’s beloved father-in-law, George, passed away and her cantankerous mother-in-law, Margaret, moved in. After nearly killing each other during their initial adjustment period, Allie and Margaret have finally buried the hatchet and have even launched a thriving home staging business together.

Today, Allie is enjoying life. That is until her twenty-two-year-old son, Cameron, unexpectedly brings home Zelda, his new fiancé. The problem is, no one has ever met or even heard of her. And when Zelda’s first impression raises more than a few red flags, Allie finds herself in unfamiliar territory.

Facing the prospect of becoming a mother-in-law far sooner than expected, and to someone unworthy of her darling baby boy, Allie’s protective instinct kicks in. And who better to turn to for guidance and support than Margaret, her former nemesis and master of the mothers-in-law’s dark arts.

Allie and Margaret launch Project Zelda, an intervention of sorts designed to show Cameron who Zelda really is and to prevent him from making a catastrophic mistake. However, with Zelda’s ingratiating behavior, Margaret’s occasional disappearances, and Allie’s doubts about turning into her own mother-in-law, will Allie find a way to reconcile her protective instincts or will history repeat itself?