'There's a place the slaves been whisperin' around called Canada,' Mammy tells her daughter one night. 'The law don't allow no slavery there.' The very next morning, a ruthless slave trader separates Julilly from her mother, taking Julilly to a plantation in the dreaded Deep South. The slave quarters there are crowded and filthy, and the slaves are as frail and thin as shadows. The cruel overseer lashes out with his whip at every opportunity. So when Julilly gets a chance to escape, she and her crippled friend Liza don't hesitate, despite their terror of what will happen if they are caught. They go disguised as boys, hiding by day and running by night. Along the way they are helped by courageous people who hide them in secret 'stations' of the Underground Railway - and they are pursued constantly by slave hunters and bloodhounds. Each close brush with danger brings them a step closer to Canada... and freedom.