Dr. Smith methodically catalogued these details, and he stepped backward, just a breath of a moment before the low hum sharpened to a whine. He tripped, and in falling his left shoulder knocked open the door to the small toilet closet. Instinctively, he writhed the upper part of his body through the narrow doorway. His thick-lensed glasses fell underneath him, leaving him practically blind. His elbows and knees were still making frenzied, primordial crawling movements when the detonation brought a wave of oblivion that almost, but not quite, preceded the pain. * * * * * A squad car from the Los Angeles County Sheriff's Department turned in the first report: _John O'Hara Smith, male, white, about 45; critically injured by explosion in house trailer; removed by ambulance to General Hospital; explosion occurred at...._ Two days later, the Sheriffs Department apparently closed the case with a one-line addition to its original report: _Explosion believed to have been caused by leaking butane connection._ But, in the interval, other agencies had entered the case. The first was the Industrial Security Office attached to the Western Division of the Air Force's Research and Development Command in the once suburban community of Inglewood, California. When Chief Security Officer Amos Busch received a call at 11:32 the morning after the explosion, he automatically noted the time on his desk pad. The call was from Pacific Electronics, Inc., a subcontracting firm in nearby El Segundo. The president and owner of Pacific Electronics was on the phone. In a tone that betrayed considerable agitation, he identified himself as Wesley Browne. "One of my research engineers--my best engineer, dammit--was nearly killed last night in an explosion ... maybe he's dead now," reported Browne, his words breathlessly treading on each other. "There's something damn funny about this...." Amos Busch wrote: Research engineer ... explosion ... nearly killed. Then he asked judicially: "What do you mean by 'damn funny', Mr. Browne?" "This engineer was working on our vernier actuating cylinder for the Atlas guided missile.... Just two days ago, he--he said he wanted me to know where his files were ... in case anything happened to him...." Amos Busch was a jowly, greying man who gave the appearance of being slow moving. But before the president of Pacific Electronics, Inc., hung up, Busch had already used another phone and the intercom to put in motion a chain reaction that would deliver to his desk the security report on Dr. John O'Hara Smith.