Deadwood breathes easier when riders arrive with precious vaccine--and word of a possible treaty with the Sioux. Awaiting Trixie's return, a pragmatic Swearengen resists counsel from a bloody-minded Farnum; results of Bullock's assay of her gold claim moves Alma to reassess her plans and sets up a confrontation between Bullock and Swearengen; and Tolliver teaches Stubbs a deadly lesson at the expense of a couple of con artists.