As if recent Capitol history (the period is late middle Watergate) weren't fanciful enough, Russell heaps up three extra layers of secret goings-on. Start with not-so-fanciful Operation Psyche, a Kennedy-created braintrust that does long-distance Rorschachs on foreign bigwigs. Add a Seven Days in May-time conspiracy (heavy on the FBI) itching to capitalize on a comatized presidency, and a ""mongrel pack"" of Chinese operatives, embittered Amerasians fathered by GIs and wangled into key US government spots. They're all out to bomb or maim Psyche's Sinologist, Tony Beaudine, especially after he takes off with a one-armed, Irish femme fatale CIA informer and begins to unravel the double helix. These engaging notions dish up a first hundred pages of credibly reluctant hero and nifty detail, with only the vamp-amputee's shamrocky or stagy locutions (""Honesty's the only weapon you possess, but it's an unloaded weapon"") a problem. But midway--along with whispers of the ""real"" motive for the Watergate break-in--it becomes obvious that there's too much plot to hold taut through the sluggish, crowded denouements. After a crash-course in tension-control with Ira Levin, Russell's ingenuity may yield more than an almost-made-it.