The instant #1 New York Times bestseller (January 2019) everyone is talking about!

People Magazine's Book of the Week . Bookish's "Must-Read Books of Winter" . PopSugar's "Best Books of Winter" . Cosmopolitan's "2019 Books to Bring to Your Book Club" . Bookbub's "Biggest Books of Winter" . Refinery 29's "Best Books of January 2019" . Crime Reads' "January's Best Psychological Thrillers" . InStyle's "7 Books That You Should Resolve to Read This January" . HelloGiggles' "The 50 Most Anticipated Books of 2019" . USA Today's "5 New Books Not to Miss" . Marie Claire's "The Best Women's Fiction of 2019 (So Far)" . Hypable's "Winter Releases You Can't Afford to Miss"

"Hendricks and Pekkanen are at the top of their game...You won't see the final twist coming." -People Magazine

"Beware strange psychologists...the authors know exactly how to play on their characters' love of danger to bring them to the brink of disaster - and dare them to jump off." -New York Times Book Review

"Slickly twisty [with] gasp-worthy final twists...major league suspense." -Publishers Weekly (starred review)

"For those who relished the creepy stalking in Hendricks and Pekkanen's The Wife Between Us, this unnerving tale will have them rethinking what secrets are safe to share and if moral and ethics really matter when protecting the ones you love." -Library Journal (starred review)

"Masterfully escalates the suspense." -Booklist (starred review)

Looking to earn some easy cash, Jessica Farris agrees to be a test subject in a psychological study about ethics and morality. But as the study moves from the exam room to the real world, the line between what is real and what is one of Dr. Shields's experiments blurs.

Dr. Shields seems to know what Jess is thinking... and what she's hiding.

Jessica's behavior will not only be monitored, but manipulated.

Caught in a web of attraction, deceit and jealousy, Jess quickly learns that some obsessions can be deadly.

From the authors of the blockbuster bestseller The Wife Between Us, Greer Hendricks and Sarah Pekkanen, An Anonymous Girl will keep you riveted through the last shocking twist.