So Frank is trying to take down the medical experiment gone awry that is Johnny Nightmare.
As they fight, Nightmare is lecturing Frank about how Frank lives, etc. and Frank is pondering things about Johnny.
Eventually, Frank defeats him by getting all of the C4 charges that Johnny planted and stuck them on Johnny Nightmare's back and detonated them.
Frank then goes to Washington to confront the man behind it all and states that they already created a soldier that can't die, and that soldier was Frank Castle himself. Frank then shoots the guy, heads home and in a bit of irony buys an ice cream cone.
This was a nice throwback to PUNISHER before he became completely inhuman, or almost. This Frank makes mistakes, has emotions, has doubts...
I liked the CAP/NIGHTMARE duality. CAP represents on side of the soldier spectrum: the ideal Frank fought for. NIGHTMARE represented what FRANK could become...
I enjoyed NIGHTMARE more that I thought I would.