E1
Luke's poor judgment nearly gets him and his friends captured by Darth Vader, and, after witnessing this bit of immaturity, both Yoda and the ghost of Obi-Wan make the decision to expand Luke's training and bring out the last of the Jedi Holocrons.
E2
Obi-Wan urges Luke to travel to Tatooine. With Darth Vader also on the hunt, it's a race for the jedi Holicrons.
E3
Luke knows there's only one way to stop the Emperor's attacks: a daring raid on Coruscant to get the holocrons back.
E4
The Emperor sends Darth Vader to destroy Luke, but Luke tries to lure him into a trap using inspiration from the last remaining Holocron.