Mirage (Large print, Paperback, large type edition)

Julie Gordon, a leading research scientist at the age of 27, has created the most exciting virtual reality program ever--a computer-enhanced, 3D voyage into the mind. When she receives the news that her estranged twin sister Samantha is in a coma, she realizes that her sister is dying, and no one can determine the cause. Now, the only thing that can save her sister is Julie's experimental program. Julie must enter her sister's mind and confront the evil lurking within--before it destroys them both.