It Takes a Thief - Season 3 Episode 15 -

In Paris, a girl as a favor to her roommate Yvonne, Al's contact, meets Al at the airport. He poses as the girl's fiancée, a stockbroker. When they go to meet Yvonne, she's already dead. Al has to find a codebook, the method of transmission and Yvonne's killer. The S.I.A. suspects the codes are being transmitted during fashion shows at Maison Trion.