What if you awoke one morning to find your wife — your soulmate, the love of your life, the person you know better than anyone else — is no longer herself? Instead, she insists she’s a seven-year-old named Lily.

This is the simple-yet-effective premise that drives I’m Not Sam by Jack Ketchum and Lucky McKee.

Narrator Patrick Burke (a nod to fellow novelist Kealan Patrick Burke) wakes after a night of passionate lovemaking to find his wife, Sam, is gone, and Lily has apparently taken over her body. What do you do when your wife breaks from reality and insists she’s a little girl? Take her to a doctor … then take her toy shopping!

The horror of caring for a loved one who is “gone, yet still here” lies at the heart of I’m Not Sam. The relationships we cherish most in life are frail, and without warning a loved one can suddenly become a stranger. Don’t think so? Talk to anyone who loves a person with mental illness or Alzheimer’s disease.

Patrick is able to “cure” his wife using a chilling and disturbing brand of therapy. Unfortunately the cure may cost them their marriage, and will forever change Patrick and Sam’s perceptions of one another.

The novella’s close, told from Sam’s point of view, feels a bit forced, but Ketchum and McKee deliver with the meat of the story, and its haunting look at the inherent frailty of our most cherished personal relationships.

BOBBY’S BOTTOM LINE: This terse thriller will leave you wanting to hug your loved ones!