Assassin's Creed Brotherhood is an action-adventure game set in Rome, where Master Assassin Ezio Auditore takes on the Templar Order. Players recruit and command a Brotherhood of Assassins to dismantle the corrupt powers entrenched in the city. The game combines stealth, combat, and leadership as Ezio rallies allies to fight alongside him. The game also introduces a multiplayer mode to the series, where players choose from a roster of unique characters with distinct weapons and assassination techniques, competing against each other online.

Following the events of Assassin's Creed II, Ezio Auditore returns to Monteriggioni only to face a devastating siege led by Cesare Borgia and the Papal Army. With his uncle killed and a powerful artifact seized, Ezio travels to Rome, the center of Templar power in Italy, to rebuild the Assassin Brotherhood and dismantle the Borgia family's corrupt hold over the city. Alone in a hostile capital, Ezio must recruit citizens to the cause, restore the Brotherhood to its former strength, and systematically eliminate Cesare's allies and resources. In the modern day, Desmond Miles relives Ezio's memories through the Animus, searching for the location of an artifact that could avert an impending catastrophe.