Frank and Kamala are going after the same supervilain, but the villain is out of both of their leagues, so they have to work together. Also, the bad guy is really freaking evil, like he's a werewolf that eats babies or something. Actually, that's pretty rad. The bad guy is a werewolf that eats babies right out of the nursery at the hospitals.
Kamala is mostly unaware of Frank's killer tendencies because he tried to keep the first couple encounters non-lethal so he could capture a goon or two and weatherboard them for information later. You know, knock-out gas, tasers, nightsticks, that sort of thing.
So, Frank figures out how to beat the bad guy and what his weakness is, and asks Kamala if she wants to come along and be his backup. Kamala is cool with this because up until this point she thinks Frank is like a super-mall-security guy who uses pussy weapons. She doesn't know that frank executed the goons he captured earlier now that he was done with them.
They go in to fight the badguy next time he's out and about. Frank pulls out the heavy weaponry and starts mowing the goons down, smiling the whole time. Kamala's all "What the hell are you doing?!?", Frank ignores her.
Kamala considers trying to protect the bad guy from Frank, but Frank says he will not hesitate to kill her too if she stands in his way. Kamala stands firm, but Frank only wounds her since he doesn't want to have to kill her if she doesn't have to. Kamala backs down and watches helplessly as Frank goes and kills the bad guy. Tons of gore, make it extra messy.
Frank disappears into the shadows where he belongs. Kamala looks at all the corpses of the bad guy and his goons and cries at the loss of life. Goes home thinking to herself that sometimes being a hero means you can't save everyone, and you have to be mentally prepared for the kind of carnage that happens if you fail.
The image of the carnage is burned in her mind, haunting her nightmares. Last shot is Kamala in bed, wide-eyed with fear.