The Sandpit by Nicholas Shakespeare is a bit of a slow burner but well worth persevering with.
John Dyer, an ex journalist, has returned from Brazil to Oxford with his son and enrolled him in the rep school that he had attended nearly 50 years ago. Life is dull and predictable in the middle class Oxford academic and school community until an Iranian, Rustum Marvar, parent entrusts John with the results of his research. When Marvar and his son disappear, the mystery unfolds at pace as different intelligence services and murky business interests encircle John and his son trying to find the potentially world changing secret.
The Sandpit is elegant, well observed and quite readable but overall a little unsatisfying.