When in Rome (1970)

MURDER TAKES A ROMAN HOLIDAY

On an exclusive guided tour of Rome's ancient ruins, a motley crew of tourists gets more than the price of admission. For amidst the serpentine passages of an underground crypt, the shady tour guide disappears, a mysterious murder occurs, and Inspector Roderick Alleyn -- undercover on an international drug bust -- must focus his keen eye on more than just Rome's breathtaking sights...