I loved this psychological thriller. I was on the edge of my seat throughout the story. I could not put this book down. I felt that Asa and Fiona were like oil and water but they also work well together. I was scared at times in this story and I was not sure who the killer was until the end. I loved the minor characters in the book. I received a copy of this book from Harlequin for a fair and honest opinion that I gave of my own free will.
I give this book a five out of five stars.

PUBLISHER DESCRIPTION
When a cold-case serial killer returns, FBI special agent Fiona Kelly has one last chance to stop him before he claims the prize he’s always wanted–her.
The sight of a goose feather at a murder scene modeled after a children’s poem is enough to make FBI special agent Fiona Kelly’s blood turn to ice. Almost two decades ago, a feather was left with her sister’s body–and with every subsequent victim of the Nursery Rhyme Killer. Now he’s back. Only this time, his latest gruesome murder is a message to the only one who ever got away: Fiona.
Finding “Rhyme” is an obsession that’s fueled Fiona’s career–and destroyed her marriage to fellow FBI agent Asa Kodiak. Now Fiona and Asa have to put their past tensions aside and work together one last time. But Rhyme is watching, and catching this killer may force Fiona to reveal her biggest, darkest secret…the one only he knows.
“Her Darkest Secret by Jessica R. Patch grabbed me in the first scene of this edge-of-your-seat suspense and didn’t let go until the end!”
–Patricia Bradley, author of the Memphis Cold Case novels