The story is about the unusual life of a young boy living in a Mississippi River town during a summer in the 1840s.
　　Tom lives with his Aunt Polly,his dead mother’s sister,along with his half-brother,Sid,and his cousin,Mary.By the second chapter,Tom’s naughty characteris revealed with the well-known fence whitewashing scene.Tom meets the new girl in town,Becky Thatcher,and falls in love with her.He begins a keen flirtation with her at school,which leads to his asking her to be “engaged” with him by lunchtime of her first day.
　　Tom’s vagabond friend Huck Finn,the town drunk’s son,asks Tom to meet him at the cemetery at midnight,to test the wart-healing properties of his dead cat.While there,the boys come across the murder of Dr.Robinson by Injun Joe during a grave robbing attempt.Muff Potter,also part of the gang,becomes a scapegoat for Injun Joe.
　　Tom,Huck,and another friend,Joe Harper,decide to run away from St.Petersburg to Jackson’s Island,in the middle of the Mississippi.There they live the life of pirates,playing day and night.After several days,the town prepares funeral services for the boys,by this time believing they are dead.The boys,however,return to town in the middle of the Sunday church services,and they are forgiven for their mischief.
　　As the murder trial of Muff Potter gets near,Tom feels uneasy and guilty over allowing a man he knows to be innocent to be charged with murder.On the last day of the trial,Tom is called as a surprise witness,and he fingers Injun Joe with the crime.Joe jumps out of the window and runs away.Tom and Huck find Joe and a stranger at a deserted house on the outskirts of town,and learn of hidden gold Joe is carrying.
　　Becky Thatcher invites many of the town’s children to a picnic.Tom and Becky go wandering in a nearby cave,and get lost.Also in the cave is Injun Joe,hiding out.Just as Tom and Becky lose all hope of finding an exit,Tom finds an opening to safety.Huck and Tom return to the cave,find Joe’s treasure,and become heroes in the town.