Limitless: Out of the Box (The Girl in the Box Book 11)

Two years after the explosive Girl in the Box Series ends, Sienna Nealon is called to London, England, where she is drawn into a murder investigation involving an old friend. Paired up with a young, handsome Detective Inspector, she finds herself in a race against time to unravel the mystery surrounding the murder as victim after victim falls to the careful, clever killer. Soon, Sienna is in a race against time to find the culprit before he sets loose a plan that will show Sienna the limits of her abilities in the most brutal way imaginable.

Her death.