Stand By The River is set in Philadelphia in 1855, and is based closely on historical characters and events. During the years leading up to the Civil War, Philadelphia was a hotbed of anti-slavery activity. While Abolitionists fought the slave power in the political arena, workers on the Underground Railroad provided aid to the flood of fugitives from the south.

The action begins in Virginia, where Jane Johnson, the slave of diplomat John Wheeler, learns that Wheeler will be taking her through Philadelphia on his way to a diplomatic assignment overseas. Unlike Virginia, Philadelphia is free territory. Having lost her husband and eldest son to the auction block, Jane swears to herself that she will take this opportunity to escape with her two remaining boys.

The action then moves further south, where another slave, Peter, has secretly earned his freedom after many years in bondage. Though he is overjoyed at the achievement of this life long dream, he must now say farewell to his wife, Vina, who will remain behind in slavery when Peter departs.

Strangers to each other, Peter and Jane end up on the same train, traveling north to Philadelphia. Peter is going there to seek his long lost mother, from whom he was separated as a child. Jane simply hopes to escape with her children once her master brings her onto free soil.

The train is met at the Philadelphia station by Judge Kane, a pro-slavery Federal judge who has business dealings with Jane's master. The Judge is first confronted by the men and women of the Philadelphia Anti-Slavery Society, including William Still, the young African American clerk to the society.

After breaking up the demonstration, the Judge proceeds to meet the train. Peter leaves quickly to search the city for his family, but Jane is taken by her master to the waterfront, where they will wait for the Camden ferry to take them to New York. Along the way, Jane tries desperately to find someone to help her without her master noticing. Finally, William, who is passing on an errand, sees her, and, realizing that she is closely watched, rushes back to the Anti-Slavery Society seeking reinforcements.

The men and women of the Anti-Slavery Society then argue about whether or not to attempt a rescue of Jane. Eventually they conclude that it will be safer to send word to New York and have their associates plan a rescue when Jane and her master arrive. But at that moment, Peter walks into the office. When he tells his story, William realizes that this is his own brother, left behind in slavery when his parents escaped years before. When William tells Peter the truth, Peter is so alarmed at this unlikely coincidence that, suspecting some foul play, he flees the office in fear and quickly disappears into the streets.

Angry and heartbroken at this cruel turn of events, William throws caution to the winds and leads the group to the Camden ferry and, in a dramatic confrontation, rescues Jane at the last possible moment. She is put into a coach and sent into hiding. Returning from the ferry, William tries to find Peter, but within minutes, he is arrested and charged with theft and riot for his part in the rescue of Jane Johnson.

As the second act starts, Jane Johnson and her children flee north. We learn that the trial of William Still has become a national phenomenon, pitting the values and the laws of North against South. Wheeler prepares a Federal case against Still for publicly humiliating him. Meanwhile, with the help of William's friends, Peter makes a desparate attempt to bring Vina north.

The fate of William, Jane, and Peter's wife Vina hang in the balance as the play comes to a dramatic conclusion.