The Miller and his wife live with their 2 children at the mill in Trumpington. They were then visited by two students from Cambridge, John and Aleyn. The students were there to take their manciples place and to personally deliver the grain back to the school.
While the students were waiting for him, the Miller set their horses free. The Miller then finished his job and bagged the meal. The boys then realized their horses were gone and run after them. While they were looking, the Miller stole half of their cornmeal. The two boys finally found their horses and begged the Miller to stay the night.
To get back at the Miller for stealing their grain, Aleyn has sex with the Millers daughter while everyone was sleeping.
John followed Aleyn's example and moved the baby cradle to the foot of his bed so that when the Miller's wife got up at night she would accidentally get in the same bed as him. John then had sex with the Millers wife.
Aleyn gets out of bed with the daughter, and climbs into the Miller's assuming it is the one shared with John (since he did not feel a baby crib and did not know of what John did). He then brags about what he did and the Miller angrily wakes up and punches Alan in the face.
The Miller tripped on his wife, and she beat him with a stick thinking it was one of the students. The students then ran off with their cornmeal and their horses.