Set before the events of the TV series, this prequel novel follows Eleven's mother and her time as a test subject in the MKUltra program.

A mysterious lab. A sinister scientist. A secret history. If you think you know the truth about Eleven's mother, prepare to have your mind turned Upside Down.

It's the summer of 1969. The world is changing, and Terry Ives isn't content to watch from the sidelines. When word gets around about an important government experiment, she signs on as a test subject.

But behind the walls of Hawkins National Laboratory – and the piercing gaze of its director, Dr Martin Brenner – lurks a dark conspiracy. To face it, she'll need the help of her fellow test subjects, including a mysterious young girl with unexplainable powers...