From 2014: By day, Marc Guggenheim is on the writing staff of the most excellent superhero drama, “Arrow,” on The CW. It takes place in a world of corporate intrigue, government corruption and, oh, yeah, this guy with superhuman physical attributes and an astounding talent with a bow and arrow. By night, Guggenheim is a writer of fiction, having just published his first novel, Overwatch, about a super-secret, out-of-control spy agency operating within the CIA without the CIA even knowing of its existenc