Batman: Odyssey, a singular and epic Batman tale, collects Batman: Odyssey #1-6 (Vol. 1) and #1-7 (Vol. 2). Out of print except in a $100 omnibus.
From the publisher:
Neal Adams, one of the most acclaimed Batman artists, has defined the Caped Crusader for decades and fans have long been clamoring to see him draw the Dark Knight once more. Now, from the legendary creator comes a Batman tale like you've never seen before!
When a series of seemingly unconnected events brings Batman close to killing a man for the first time, Bruce Wayne must embark on a journey of self-discovery... which also reveals shocking secrets about Batman's enemies and allies alike.
From a secret chamber in Arkham Asylum to a hidden world below our own, this weird, wild journey will answer once and for all the question, "Can a Batman who kills still be Batman?"