Daredevil/Batman: Eye for an Eye is an Elseworlds graphic novel published by Marvel Comics in 1997, written by D. G. Chichester, with art by Scott McDaniel. It is a standalone, non-canon crossover between Marvel's Daredevil and DC Comics' Batman.
Plot
Daredevil and Batman must work together to defeat Two-Face, who partners with Marvel villain Mr. Hyde. Batman pursues the two villains to New York, where Daredevil is investigating a series of thefts of computer equipment, which leads him to the same criminal pair. Batman and Daredevil initially clash, even coming to blows, before ultimately resolving to work together.
Two-Face and Mr. Hyde have stolen a computer chip which acts as powerfully as a human brain, but the chip needs to be housed in organic brain tissue. Two-Face's plan, therefore, is to trick Mr. Hyde into consuming large quantities of a specific drug, which will both speed up the formation of the chip and eventually kill Hyde, allowing Two-Face to harvest the chip from Hyde's brain.
It is also revealed that Harvey Dent was once friends with Matt Murdock: prior to his disfigurement, Dent believed in giving criminals a chance at rehabilitation, while Murdock believed in final justice. Having since come around to Dent's philosophy, Murdock, as Daredevil, manages to talk Two-Face out of killing Hyde when the four face off.