Isaac's life is very similar to his father Abraham's. He, too, leaves Canaan to escape a famine, makes a covenant with God, tries to pull the sister-wife switch, gets super rich, cuts a deal with Abimelech, and argues over wells.
Fast forward. Isaac is old and his vision is going. He calls for Esau and wants to bless him after Esau hunts and grills up some meat for him.
Rebekah overhears the whole conversation and reports the details to Jacob.
She urges Jacob to do it himself so that he might acquire the blessing. Isaac won't know the difference. He's blind.
She dresses Jacob up in his brother's clothes and puts some animal fur on his hands and back. Then she hands Jacob the food.
Jacob goes to his old, near-sighted dad and commits what we would today call identity theft by pretending to be Esau.
Isaac eats and downs some wine. Then Isaac kisses Jacob, and notices that he smells just like Esau (Jacob is wearing his clothes, after all).
Finally, Isaac gives Jacob his blessing.
Then tornado-like confusion ensues when Esau returns from his hunt. Isaac and Esau realize what Jacob did, and Esau's none too happy about it.
Rebekah overhears Esau plotting to kill Jacob and tells Jacob to take off and go hang out with the extended family in Haran.