Frayn, noted for his waggish plays (Noises Off, Benefactors) as well as his novel, The Trick of It (1990), turns a British civil servant's investigation into an unexplained 15-year-old death into a winsome, whimsical comedy. Middle-aged nonentity Brian Jessel is assigned to look discreetly--and forestall the tabloid journalists' recurring interest- -into the 1974 death of equally minor government minion Stephen Summerchild, who evidently fell from an Admiralty window onto M06D property, becoming an everlasting mystery. Did Summerchild fall accidentally, jump, or get pushed? And why should his blameless life have ended so irregularly--contact, perhaps, with foreign powers? Tracking down and sifting through the reports Summerchild dutifully filed during the last months of his life, Jessel follows his footsteps as his assignment--a study of contemporary ``quality of life''--takes him to Elizabeth Serafin (an austere Oxford philosophy don who demonstrates to him Socratically that happiness is necessarily a subjective concept) and through the belly of dialectic to an unlikely and desperate love affair with Dr. Serafin, documented with amusing and maddening ellipses on a series of typed transcripts and audiotapes. All the while, Jessel, whose small son barely moors him in his present life, finds himself dissolving into Summerchild, wondering why Millie Summerchild, whom Jessel had known for years from an amateur orchestra, had dropped out of sight a week before her father's death, and what Dr. Serafin's three sons are up to that's driven their mother to such grief. Whimsically charming to the end, but grave and sweetly sad as well--altogether a very British affair.