Midnight Man. Number 43 in Series

Law-enforcement officials think they've seen everything until they encounter Elmo Winkler, the inventor of a substance that can make anything invisible. Wimpler has found his niche in life by dropping out of sight - literally - and going on a killing spree with a device that crushes skulls. As top-secret agents Remo and Chiun stalk this invisible serial killer, Wimpler's ultimate target materialises: a deposed Middle Eastern sovereign with a $25-million price tag on his head.
The United States has granted him asylum, and it's up to Remo and Chiun to bring the curtain down on Wimpler's organisation before he sends the monarch to Kingdom Come. But his victims are multiplying, there are no clues in sight and authorities are groping in the dark. Under suspicion themselves, Remo and Chiun set out to play blindman's buff with the killer no one can see coming .