Murder by the Sea by Lesley Cookman
When a body is discovered on a rocky little island in the middle of Nethergate Bay the media swoop on the seaside town. Soon an enquiring hack discovers that local resident Fran Castle, has previously aided the police using her psychic abilities. Brought into the investigation, Fran naturally asks her friend Libby Sarjeant to help, but they soon find themselves up to their knees in more mud and murder than they could possibly have anticipated.