New from the author of Color Blind...FBI profiler Jenna Ramey has synesthesia, a neurological condition that causes perceptions of color to flash through her mind, triggered by seemingly unrelated stimuli. But she has learned to understand and interpret these associations. They help her do her job. They can help save lives...

A little girl has witnessed a mass shooting. What she knows may be the key to finding the man responsible. Jenna has been tasked with drawing her out, figuring out what she saw, what she remembers, what it means.

But Molly is an unusual child. She is sweet and bright, and eager to help, but she has a quirk of her own: an intense preoccupation with numbers. It helps her notice things that others don't. It also leads Jenna into a maze of speculation that could turn into a wild goose chase while the body count continues to rise.

Jenna and Molly view the world through their own filters. In some ways, they speak different languages. Now Jenna must learn to communicate, to break Molly's code, to understand the mind of a murderer...