Plot summary
As Gus confronts Shawn over the diamond ring he just discovered, a valuable shipment of artifacts is stolen from a museum leaving the curator ( John Rhys-Davies ) furious, so Shawn calls in Pierre Despereaux ( Cary Elwes ) to help them catch the thief ( Mädchen Amick ) who stole the shipment, but it's an old dagger that she was really after. As usual, nothing is what it seems since Despereaux is involved, and they understand that the dagger is the key to a much bigger mystery.
Credits
Adapted from Wikipedia contributors, Psych season 6. HTML formatting and reference markers removed.