For the experts at Diageo, finding gems among the spirits giant's whiskey holdings is a delicious treasure hunt. Recently Ewan Morgan, Diageo's Master of Whiskey—a title he seems born to, having grown up in Speyside, Scotland, where his father was a manager at Highland Park and his grandfather a brewer at Cardu—was tipped off to the riches that lay in the rickhouse at the company's Stitzel-Weller distillery in Louisville, Kentucky. Turns out that Stitzel-Weller manager Andrea Wilson had some brilliant orphans on her hands—barrels of 26- and 20-year-old Kentucky straight whiskeys that, through happenstance, had never been bottled. Forthwith, Diageo created Orphan Barrel, a new series of "found" one-off whiskeys now on its third release. Each is a unique expression of the history and life of the casks. Aged 26 years, Old Blowhard ($150) is the big, oaky show-off of the trio. The newest blend, Rhetoric ($85), is creamy with a nutty—and coconutty—character.