  Non-locality of the type first elucidated by Bell in 1964 is a difficult
concept to explain to non-specialists and undergraduates. Here we attempt this
by showing how such non-locality can be used to solve a problem in which
someone might find themselves as the result of a collection of normal, even if
somewhat unlikely, events. Our story is told in the style of a Sherlock Holmes
mystery, and is based on Mermin's formulation of the "paradoxical" illustration
of quantum non-locality discovered by Greenberger, Horne and Zeilinger.
