THE UNDETECTED Nothing can possibly be more baffling than a crime in a sealed room ... but what if the investigator happens to have an open mind? II TOOK A QUICK LOOK around the apartment, even though I already knew what I had to know. Gordon Andrews had been slain in his sleep by the quick thrust of some rapierlike instrument. There was no sign of any struggle. The wall safe stood with its door open and its contents missing. Every door and window was closed, locked, burglar-bugged, and non-openable from the inside; the front door had been forced by the police. Furthermore, it had been raining in wind-whipped torrents for hours, yet there was no trace of moisture on any of the floors. Of course no one had heard a sound, and naturally there were no fingerprints. Police Chief Weston sp

