The New Adventures of Lucky Luke - Season 1 Episode 46 Crown Witness

A judge requires Lucky to escort New York zoology professor, Oscar Tinyboots, a snail expert, to St. Bob, Kansas. He's the star witness against Smiley Laughter, having killed a protected animal. Smiley, a gangster, has never lost a trial because he has all the witnesses murdered. Oscar's bossy wife, Mimi, and Luke escort Oscar, first masquerading as soldiers. When the leave, the platoon commander tries to catch the deserters, so they venture into tribal Indian land. There the humble snail suddenly becomes vital.