Apothecary Rose. The First Owen Archer Mystery, Paperback/Candace Robb

But there seems to be a common thread - the herbal remedies dispensed by Nicholas Wilton, Master Apothecary. But when a highborn nobleman dies after taking the same potion the authorities decide to act.Dispatched to York, in disguise, to unravel the mystery, Owen Archer, former Captain of Archers, apprentices himself to the Apothecary.