The bland, slow debut of art-historian/sleuth Cyrus Finnegan--a stubbornly unengaging fellow who chats on and on (as does everyone) in this busy but ineffectual attempt at an old-fashioned-British mystery. The murder victim: very young Charles Knowles, the supposed painter of the pictures shown in the opening show at London's new Princess Gallery. But Finnegan, in talk-a-thons with chum Supt. Graham and housekeeper Helga, doubts that teenager Charles really is the artist--especially when it appears that Charles' uncle is manic art-critic Tony Kershaw and his father is a shady international art-dealer. And though the top suspect for the murder is equally shady gallery-owner/psychiatrist Dr. Edinburgh, he himself is soon murdered too. So, while Williamson scatters red-herrings right and left (drug-dealing, adultery, etc.), Finnegan closes in on the very obvious, furiously-hinted-at Truth: a matter of stolen/smuggled art, with one nice touch in the method of concealment. Fair plot ideas, then, and a few convincing gallery details--but the nonstop dialogue is flat (especially when used for leaden exposition); the eccentric characters are lifeless; and even the London locale (so often a saving grace for Anglophiles) is too unconvincing to redeem this charmless, hard-working first novel.