[1] Azzarello and Bermejo had previously worked on a similar take on Superman's archenemy in Lex Luthor: Man of Steel, and Joker grew out of a discussion following completion of that project.

With the help of Harley Quinn, Joker kills one of his former henchmen and claims his intention to make Gotham City his again.

Joker embarks on a killing spree, murdering many thugs who stole his money, turf, and bizarre sense of reputation.

He is then informed by Penguin that Harvey Dent, his chief rival for control of Gotham, is avoiding him, enraging Joker.

Once on the road, they are attacked by crooked off-duty cops hired by Dent, and Frost saves Joker's life in the scuffle.

IGN commented that "Brian Azzarello and Lee Bermejo's Joker is a deeply disturbing and completely unnerving work, a literary achievement that takes its place right alongside Alan Moore's The Killing Joke as one of the few successful attempts to scratch beneath the surface of the Joker's impenetrable psyche".

[4] AICN noted that "the story is compelling, especially the gut-wrenching showdown at the end of the book, and the art is mouth-wateringly good".