When Caroline learns that British spies may be lurking in Sackets Harbor, she is worried. Then, a long lost friend of Papa's shows up in town. Papa is delighted to give him a job at Abbott's Shipyard, but soon, strange things start going wrong. Caroline is sure a spy is making trouble at the yard—but is it one of Abbott's trusted workers, whom she has known all her life, or could it be Papa's dear friend? An illustrated "Looking Back" section discusses the role of spies in the War of 1812.

Caroline has an important package to deliver for her father in the big city of Albany. That means a three-day stagecoach trip with her friend Rhonda! The other travelers, including a charming magician and a beautiful young woman with a sad past, fascinate the girls. But when Caroline's precious package goes missing, she realizes the culprit must be a fellow passenger. Will she unmask the thief in time, or will her promise to Papa be impossible to keep?

The War of 1812 is still raging when Caroline goes to visit her cousin Lydia and Uncle Aaron's farm deep in the woods. While there, she finds evidence that someone is smuggling precious supplies to the British. She can't believe anyone would help the enemy during wartime! Even could the traitor be her own uncle? Includes an "Inside Caroline's World" essay about smuggling during the War of 1812.