1837 on the Ohio River. May Bedloe is a seamstress to her cousin, the flamboyant actress Comfort Virtue. When they board the doomed Moselle their paths cross with Mrs Howard, a wealthy abolitionist and notorious opportunist. Mrs Howard quickly lures Comfort to her cause; a cause, it seems, that has no use for May. Casting out on her own for the first time, May lands a job on Hugo Cushin's wondrous Floating Theatre - a flatboat that sails the Ohio performing plays to the townsfolk along the way. Based on the history of the underground railroad.