The serpent tempts Eve into eating the forbidden fruit from the Tree of the Knowledge of Good and Evil, and she gives the fruit to Adam, too. God expels them both from the Garden of Eden and curses them.
Genesis 3:6 [King James Version]
"And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat."