A device that can save a life is also one that can end it.

Kadence, a new type of implanted defibrillator, misfires in a patient visiting University Hospital for a routine medical procedure, causing the heart rhythm problem it's meant to correct. Dr. Kate Downey, an experienced anesthesiologist, resuscitates the patient, but she grows concerned for a loved one who recently received the same device—her beloved great-aunt Irm.

When a second device misfires, Kate turns to Nikki Yarborough, her friend and Aunt Irm's cardiologist. Though Nikki helps protect Kate's aunt, she is prevented from alerting other patients by the corporate greed of her department chairman. As the inventor of the device and part owner of MDI--the company he formed to commercialize it--he claims that the device misfires are due to a soon-to-be-corrected software bug. Kate learns his claim is false.

The misfires continue as Christian O'Donnell, a friend and lawyer, comes to town to facilitate the sale of MDI. Kate and Nikki are drawn into a race to find the source of the malfunctions, but threats to Nikki and a mysterious murder complicate their progress. Are the seemingly random shocks misfires or are they attacks?

A jaw-dropping twist causes her to rethink everything she once thought she knew, but Kate will stop at nothing to protect her aunt and the other patients whose life-saving devices could turn on them at any moment.

Perfect for fans of Robin Cook and Tess Gerritsen