Agatha Raisin and the Witch of Wyckhadden (Agatha Raisin #9) by M.C.Beaton

There is nothing more depressing for a middle-aged lovelorn woman with bald patches on her head than to find herself in an English seaside resort out of season. Agatha Raisin, her hair falling out after a run-in with a hairdresser-cum-murderess from a previous investigation, travels to an old-fashioned hotel in order to repair the damage away from the neighbors in her all-too-cozy Cotswolds village.

Unhappy about the slow results and prompted by the elderly residents of the resort, she consults the local witch for help. Agatha purchases a hair tonic (and a love potion, just in case!) and is soon sprouting hairs and capturing the fancy of the village police inspector. But the quiet town is stunned by the murder of the witch. Which one of the graying guests is capable of such a brutal crime? The brassy yet endearing Agatha won't stop until she finds the culprit--and, of course, a little love, too.