The setting is pure sci-fi, full of spaceships and high tech. And within the military of some world there exists the `angel division'. A group assigned with a great number of special missions. However before you get an image in your mind let me tell you that neither the missions, or indeed the group, are anything like you might expect. Instead you've got 5 females with an excess of personality, some quite varied abilities, and a cavalier disregard for any sense of uniform or military. And the jobs they get match this, they're not so much high status and ultra-violent as all the weird jobs that the `sensible' parts of the army don't want to go near.
The missions themselves vary a lot. Some of them are fun, some of them are dangerous and many of them are both. And should it be a quiet day you can rely on the group to get in trouble all by themselves. While it's not really covered in the series it also seems that they can be hired, so often they are visiting different parts of this interesting universe having `adventures' at the hands of employers almost as weird as they.