The Wild Wild West - Season 4 Episode 13 The Night of the Pelican

West and Pike receive a note to meet a woman at a Chinese restaurant in San Francisco with a promise of information about the militant Din Chang who has recently stolen a supply of fulminate of mercury from a military arsenal. Unfortunately, the woman is killed before they can talk to her and the only word she utters is "Pelican". To further complicate matters, the only person they manage to capture is supposedly still serving time at Alcatraz. Since it seems that Alcatraz and the woman are the two pieces they have of the puzzle, the two split up to track down Chang before he can use the volatile mercury.