Death of an Addict by M. C. Beaton
From the author of the Agatha Raisin television series...DEATH OF AN ADDICT: A Hamish Macbeth MysteryFormer drug addict Tommy Jarret rents a Scottish chalet to check out reports of a sea monster. But when he is found dead of an apparent drug overdose, constable Hamish Macbeth suspects foul play. Teaming with Glasgow Detective Inspector Olivia Chater, Macbeth goes undercover and dives into the underworld to root out a cartel secretly entrenched in the Highlands.