Foundation and Empire

In the second book, the Foundation has grown in power to rival the dying Empire. With superior technology, and access to energy that other planets lack, it receives tributes from the rest of the Galaxy, all in accordance with the Seldon Plan. But this plan does not take into account the rise of a rogue individual: the Mule, a warlord with the power to manipulate thoughts and emotion. All that stands between the Mule and total conquest of the Galaxy is the mysterious Second Foundation; but its location is a secret that others will die to protect.