It's loosely based on SG1 except set in a fantasy universe. It's a world where an ancient race of winged demons opened a bunch of Gates to other dimensions scattered all over the continent and then, over a thousand years before the present, suddenly went nearly extinct. The survivors managed to leave descendents by interbreeding with the still-primitive humans, but this caused their descendents' appearance and magic abilities to mutate.
Every once in a while a demon child is born that is considered a "throwback" to the ancient demons because it can see the Gates, which are invisible to everyone else...and has wings. Eventually, one of these throwbacks decided to start investigating what was on the other side of the Gates, and she soon developed a team of professional Gate-explorers. All they know about the ancient demons is that they nearly all died out suddenly, and they're afraid that the disaster was caused by something coming through one of the Gates. This hypothetical Gate was dubbed "Disaster Gate," and an entire village of demons and mages grew up to support the teams investigating the Gates in order to find Disaster Gate and close it.
The novel I wrote (the first in a planned series) is about a team of four Gate explorers: a bishounen throwback demon as team leader; his childhood friend, a psychic demon with honed physical combat skills; an elemental sorcerer who grew up reading books in a tower alone with his wizard master (...kind of like Rapunzel...); and a young Banisher (rather like a Slayer), a girl with the magic ability to combat devils and demons, who joined to search for her older sister who vanished through a Gate. The plot of the book is about how they explore their first Gate, which leads to a world of winged beings called angels they suspect might have some relation to the ancient winged demons.