Care of General Delivery A Man Called Shenandoah : Season 1 Episode 33

Shenandoah goes to a town near El Paso looking for a biographer, Frances Xavier O'Connell, who may have clues to who he is. There he meets the local Post Mistress, Miss Matilda (Jeanette Nolan), who eventually promises to introduce Shenandoah to O'Connell (James Doohan). However, when he finally meets the biographer, something doesn't add up.