How's this for a Washington cliffhanger? Take a crusading newspaper, the Chronicle, which toppled one president, give it an editor who talks like Ben Bradlee and walks like Jason Robards, add a monomanic, incorruptible newshound named Gunderstein, give him a story which will blow the liberal front of Senator Henderson, the man in line for the next presidency as well as the friend of the power-hungry lady publisher-owner of the Chronicle. She wants Henderson as her man in the Ova/ office. The price? To sit on the biggest story since Watergate--not a new one in novels like this: the Kennedy involvement in Diem's assassination. Gunderstein has uncovered a former ""adviser"" in the field who worked with Henderson on the job. But Robards-Bradlee, now known as Nick Gold, wants ""two sources of confirmation."" Will Nick defy his publisher and run the story? Adler spends considerable energy in defining Nick's choices and wires the reader's nerves from one edition to the next.