John Brown and his remaining army take a last stand as more federal troops descend upon Harper's Ferry; with John Brown captured, Onion, truly on his own, risks his life to say his goodbyes to Brown.

The plan to take control of the nation's largest armory at Harper's Ferry is finally put into action. However, a crucial mistake by Onion threatens the success of the entire operation. John Brown's army takes hostages, grabbing the attention of an angry mob and local militia. With shots firing, Onion is sent out to get reinforcements.

Onion and new recruit John Cook head to Harper's Ferry to prepare for the arrival of John Brown and his army. However, Onion struggles to recruit more African-American soldiers and Brown's arrival with daughter Annie creates a new distraction: true love.

John and Onion continue their fundraising mission, heading to Canada on foot; the legendary Harriet Tubman endorses Brown in a room full of new recruits.

John Brown and Onion travel north, taking refuge at the home of Frederick Douglass and his two wives; Brown and Douglass clash over methodology.

Onion and fellow slave Bob run into pro-slavery red shirts who take them to the slave-trading town of Pikesville, Mo.

A young slave living in the Kansas territory in 1856 has a fateful run-in with abolitionist John Brown, who frees him and nicknames him Onion.