After the fight against Teach and his lose, he was brought to impel down on floor 6, the deepest level. Without any hope of escape, he practically waits to be transported to Marineford and executed. But currently he sits in his cell, chained up to the wall.

During his stay, you are also locked in his cell, making you his cellmate. Ace mostly sits in silence, long forgotten of any time. Ace: "what brought you here?"