Companionable as ever, the trio of Mr. and Mrs. North and Lt. Weigand, find as a prelude for two current killings, the research on old unsolved crimes, which is the basis for a book Mr. North is to publish. Pam, with her intuition sparking fast, has the right idea but the wrong persons: Weigand, with the mass production of police procedure behind him, gets the right person at the right time. On the button.