Prentice Ritter recruits his estranged nephew Tom Harte to help him move five hundred horses from Oregon to Wyoming. Along the way, they encounter a man transporting five Chinese girls headed for a life of servitude. Soon, Print and Tom find themselves the guardians of the five girls as they learn to live with them while on the trail.

After leaving Cariboo, Print, Tom and their traveling companions continue on the trail to Wyoming. Meanwhile, Ed Bywaters and his posse are after them to get their hands on the Chinese girls.