The year is 1774, and 14-year-old Johnny Tremain is a skilled apprentice in Mr. Lapham’s humble silversmith shop. Although another boy, Dove, is two years older, Johnny is the lead apprentice and practically runs the shop on Boston’s great wharf. Mr. Lapham’s widowed daughter-in-law hopes he will marry one of her four daughters so the shop will stay in the family after Mr. Lapham dies.
Johnny’s mother apprenticed him to Mr. Lapham two years earlier when she grew ill and knew she was going to die. Since then, Johnny has proven himself to be a responsible, gifted, but prideful, apprentice. He lords his skill over Dove and a younger boy, and revels in his status in the Lapham house.
Mr. John Hancock, who owns the wharf and many of the warehouses and ships along it, comes to the shop to request a sugar basin be made to match a creamer in his set. Although Mr. Lapham had made the originals, he wonders whether he still has the skill to create the intricate handles. Johnny assures Mr. Hancock that the order will be done by the following Monday. He knows he can do the work.
While Mr. Lapham is able to make the basin in time, Johnny struggles. Though he copies the handles on the creamer exactly, the wax molds he creates do not look correct. Desperate, he takes his work to Paul Revere, Boston’s most renowned silversmith. Revere praises Johnny’s work, but agrees with him that the proportions are not correct. The sugar basin has a different curve than the creamer, and so the handles must be altered slightly. Johnny leaves Revere’s shop elated both with the information to fix the handles and with the knowledge that Mr. Revere admires his skills and wants to buy his apprenticeship from Mr. Lapham.
On Saturday afternoon, Johnny sets about to cast the handles, but Dove, in an effort to show Johnny up, brings him inferior coal that will not burn hot enough to melt the silver. When Johnny derides the older boy, Mr. Lapham steps in to reprimand him. He has tried, repeatedly, to curb Johnny’s pride, as he believes it is a sin. He warns that God will punish Johnny if he continues to behave so arrogantly. Lapham refuses to let Johnny work on the basin until Monday morning.
Both Johnny and Mrs. Lapham are distraught. The basin will not be ready for Mr. Hancock on time, and they will lose valuable business. On Sunday afternoon, while Mr. Lapham attends church, Johnny sets about to cast the handles, even though it breaks the laws about working on the Sabbath.
Dove, again wanting to show Johnny up, brings him a cracked crucible in which to melt the silver. As the silver melts through the crucible, Johnny rushes to save it with his outstretched hand. He slips and his hand lands in the hot molten liquid. In an instant, his life is irrevocably changed. His thumb fuses to his palm, and he can no longer be a silversmith.
It takes Johnny several weeks to recover from his wound, during which Mr. Lapham allows him to stay at his house, but Mrs. Lapham’s generosity is not so great. Useless to her now, she sees him only as a lazy boy taking food from the mouths of her poor daughters. Mr. Lapham assures Johnny he will always have a home, but encourages him to try to find work elsewhere to support himself.
Desperate but still proud, Johnny spends weeks searching for employment. His pride keeps him from taking menial work, and his injury prevents him from doing anything skilled. He makes friends with an older boy, Rab, who works in the printing shop of his uncle, Mr. Lorne. Rab says they have work for him, but it is unskilled. Johnny, however, says he wants to prove he can find a skilled job.
Before she died, Johnny’s mother had given him a beautiful silver cup with the Lyte family emblem on it. The Lytes are a wealthy family in Boston. She told him never to show it to anyone, but that if he were ever in dire need, he should approach Mr. Lyte and show him the cup. Johnny kept it secret from everyone but Cilla Lapham, his master’s granddaughter and his only real friend. He also confessed to her that his full name was Jonathan Lyte Tremain, and that he must somehow be related to the Lytes.
Now unable to find work and being harassed by Mrs. Lapham, Johnny approaches Johnathan Lyte, a rich merchant. Unimpressed with Johnny’s story, Mr. Lyte insists Johnny bring the cup to his mansion the following day. When he does, he is shocked to find Mr. Lyte has brought the sheriff in and has Johnny arrested for stealing the cup.
Johnny’s new friend Rab comes to his aid. He and his uncle are members of the Sons of Liberty, a secret organization working toward freeing the American colonies from British rule. Mr. Lyte asks the judge to give Johnny the death penalty as a deterrent for other young thieves, but Rab arranges to get Cilla to the courtroom so she can testify to seeing the cup before the date Mr. Lyte said it had been stolen.
They also bring Cilla’s younger sister, Isannah, to testify. Although she had not seen the cup, she cries tears and tells the judge she did. The child wins over the judge with her angelic beauty and innocence. Johnny’s case is dismissed, and he is set free. In gratitude for Rab’s help, Johnny takes a job with the print shop and begins delivering copies of its seditious newspaper, The Boston Observer. He also learns how to ride a horse so he can deliver the paper to nearby towns.
Over the coming year, Johnny becomes a valuable help to the Sons of Liberty. He regularly rides to deliver messages to the surrounding towns about secret meetings held in the Observer’s office. He also helps the stable boys at the hotel across the street, which houses many British soldiers. He learns about troop movements and British plans and reports them back to the Sons of Liberty.
When Dove is let go from Mr. Lapham’s shop, he gets a job taking care of a British officer’s horse. Although Johnny had thought he would never forgive Dove for causing the accident that ruined his hand, he finds himself having to befriend his enemy so that he can gain even more information for the rebellion’s cause. As Johnny gains the trust of the Sons of Liberty, he is even allowed in on one of their major demonstrations.
In an effort to protest England’s taxation on their imported tea, Johnny, Rab and several other boys dress up like Indians and board a British ship docked at the wharf. England will not allow the ship back if it still has the tea aboard, and the Bostonians will not let the tea off the ship. The boys, under the guidance of the Sons of Liberty, destroy only the crates of tea and throw them overboard into the harbor. Then they clean up the mess on the decks so that the ship is in pristine condition.
The port of Boston is closed as punishment for the tea. No ships are allowed in or out except for British warships. England hopes to starve Boston into submission. As tensions begin to rise, the Sons of Liberty prepare to take arms against the British army. Johnny gives a British deserter some of his clothes in exchange for his musket, and then gives the gun to Rab, who has been training with the militia. More soldiers arrive, and by April of 1775, it is clear the British are planning to battle.
Johnny has remained in contact with the Lyte family through his friend Cilla Lapham, who now works for Mr. Lyte’s daughter, Lavinia. As the Lytes prepare to flee Boston, Lavinia admits that after investigating his claims, Mr. Lyte now believes Johnny’s story. He is Mr. Lyte’s great-nephew and will receive, in writing, verification of his heritage. Should he want, once the battle with England is over, Johnny can claim rights to the Lyte mansion and property.
Johnny learns from Dove that the British hope to raid ammunition caches in the nearby towns of Lexington and Concord. Johnny gives the message to Billy Dawes and Paul Revere when it is clear the British are using boats to move their troops out quickly. The two men ride out to warn the surrounding towns that the British troops are coming to fight.
The following morning, Johnny learns that the British troops won the day in Lexington, and they already moved on to their next goal. Johnny fears for Rab, who left with the militia the previous week. He sneaks out of Boston to find him, only to discover that he was shot at Concord. A friend, Dr. Warren, takes Johnny to see Rab in a makeshift hospital for the wounded. Rab muses about their first meeting and then tells how he never even got to fire the musket Johnny gave him. Knowing he is going to die, he bequeaths the gun to Johnny.
Later that night, Dr. Warren tells Johnny that he could operate on his hand. It may never be healed enough to be a silversmith, but Johnny will be able to use a gun and help to fight for the colonies’ freedom.