Castle has a lot going on. He's trying to finish his new novel Heat Wave and trying to figure out how to fix things with Beckett. But circumstances force the pair back together to investigate the mysterious murder of a man found dead, tangled in the limbs of a tree.
Barack Obama becomes the first president to appear on the Late Show while in office. During his 30+ minute sit-down with Dave, President Obama discusses the economy, foreign policy, and health care reform. Quote Dave: "Your job is more difficult than my job."
When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens Leonard's hope for some romantic time with Penny and the guys' friendship with Sheldon.