She found a death note and the ever-so cunning L couldn't find her. Then she got a shinigami to kill L. THEN Near and Mello got into the case. And after a bunch of SAKAJO! and I knew it! I knew it! I KNEW IT!!! and MUAHAHAHA, and "It's a trap! The whole thing is a set up!", Near finds out that she was Kira and then Matsuda shoots her. Before they can throw her in jail, Ryuk kills her. Then Misa jumps off a building.
What a happy story.