Fullmetal Alchemist Episode 20: Soul of the Guardian
Episode 20 of 51 of Fullmetal Alchemist, aired February 20, 2004, 25 minutes. Available with English subtitles and dub where released.
Episode summary
The battle in the Fifth Laboratory continues. Separated, each now face a formidable foe: Ed faces off with Number 48 while Al deals with the insane Number 66. After an exchange with Number 66, though, Al soon comes to question his very existence.