Death Undertow — Dennis Casley

Legend had it that the still, dark pool, separated from the Cornish sea by only a great sand bar, claimed a victim regularly, so the locals nodded meaningfully when an Indian diplomat who was attending a seminar on rural development in the Commonwealth disappeared during a midnight swimming tryst.
But Chief Inspector Odhiambo, sent from Kenya to England to attend the seminar, suspects that a killer stalks the rugged cliffs, and a ghastly discovery soon confirms his belief.
Odhiambo finds his personal life becoming entangled with that of a vivacious administrative officer at the Polsand Centre as they track the killer with a suspicious police force watching their every move.
A hurricane and nightmarish boat trip with a sinister local boatman place Odhiambo in great danger and add to the number of murder victims. The mix of local traditions with Commonwealth visitors proves to be an unstable compound, and the atmosphere becomes increasingly threatening until Odhiambo, in an uneasy alliance with local Chief Inspector Pendham, places himself in danger once more to force matters to a violent conclusion.