Ellen is a timid ten-year-old girl living in British-occupied lower Manhattan with her mother and grandfather. Grieving the loss of her father and the disappearance of her older brother in the war, she is deeply frightened of the bustling city streets, the occupying British soldiers, and local bullies. Despite her fear, she agrees to disguise herself as a boy and travel to New Jersey to deliver a covert message for the Patriot cause.

Grandfather is a cheerful, sandy-haired patriot who works as a barber and wigmaker in New York. He caters to a large clientele of British officers, using his affable persona to overhear sensitive military plans without drawing suspicion. When a sprained ankle prevents him from making a crucial courier run, he places his complete trust in his granddaughter to finish the mission.

Mother is a protective woman grieving the recent death of her husband at the Battle of Brooklyn Heights and the disappearance of her son. She adheres strictly to the gender norms of her era, firmly believing that a young girl should not engage in physical altercations or dangerous espionage. She worries constantly about her family's safety under British occupation.

Higgins is a sad-faced, homesick British soldier stationed in the American colonies. He takes a fatherly interest in Ellen because her disguised appearance reminds him of his own son, Tom, back in England. He stands up against his fellow soldiers' bullying and provides Ellen with crucial encouragement during her frightening journey.

Dow is a husky, aggressive British soldier with a dirty fringe of scraggly hair beneath his black hat. He views the American colonists with contempt and acts as a blustering antagonist toward Ellen during her boat ride. He frequently uses physical intimidation to try and take what he wants and openly mocks the Patriot forces.

Dicey is an impoverished, rough-faced neighborhood girl with tangled pale hair and tattered clothes. She spends her mornings at the water pump bullying other children, particularly targeting Ellen, whom she resents for having warm clothes and a secure home. Her intimidation forces Ellen to walk twice as far every morning just to fetch water.

Mr. Shannon is a tall tavern owner in Elizabeth, New Jersey, who works alongside Grandfather in a covert network of Patriot spies. He uses his establishment, the Jolly Fox Tavern, as a front to gather intelligence and relay messages to General Washington's forces, operating with extreme caution in a distrustful environment.

Mrs. Shannon helps run the Jolly Fox Tavern in Elizabeth. She maintains a cheerful, accommodating facade for the British soldiers who frequent her establishment, playing the part of a loyalist to protect her husband's espionage activities. Behind closed doors, she works diligently to support the Patriot spy network.

Murdock is a New Jersey local who travels the roads trading goods. He holds strong anti-British sentiments but grows highly suspicious of Ellen when she dives into a stream to save a soggy loaf of bread, wondering if she is secretly transporting something valuable.

Mistress Murdock is an anxious, overprotective mother of four sons who lives half a mile from Elizabeth. Fearing the violence of the war, she vehemently opposes anyone traveling the roads at night and attempts to forcibly remove Ellen's wet breeches to dry them by the fire, inadvertently causing Ellen to flee.

Ezra is Ellen's fifteen-year-old brother who fought alongside their father at the Battle of Brooklyn Heights. He went missing after the battle, leaving his family to wonder if he retreated to Pennsylvania with General Washington or if he is languishing on a dangerous British prison ship.

Aaron is a young boy on the streets of New York who, along with his friend Arnie, targets Ellen while she is disguised as a boy. He steals her blue-wrapped loaf of bread and chases her through the city, forcing her to run through unfamiliar streets to escape.

Arnie is a rowdy street boy in New York who participates in bullying Ellen and tossing her bread back and forth with Aaron. His actions inadvertently push Ellen to find her inner speed and fight back.

General George Washington is the commander of the American forces who has recently suffered major defeats and been pushed out of New York by the British army. He relies heavily on the covert intelligence provided by ordinary citizens to plan his next military movements.

Grimsby is a trusted friend of the Shannons who helps safely transport Ellen back across the bay after she successfully delivers her message. He proudly sings Yankee songs to keep morale high.

Gallop is a trusted ally of the Shannons who accompanies Ellen and Grimsby on the return journey across the bay. He sings rebellious songs about the American cause as they pass British ships.