I should have realized this was a book farther in the series than I originally thought, but DC Super Hero Girls: Search for Atlantis is book seven in the series. However, while it is a standalone novel, you should probably have some basic knowledge who the characters are. Therefore, finding the first few books would be your best bet.
Author and illustrator Shea Fontana and Yancey Labat continue the Super High School girl’s stories with this graphic novel. We see all the girls of the DC world: Wonder Woman, Batgirl, Bumblebee (new to me), Supergirl, Katana (is she a hero? Also not familiar with her) and even a villain or two (this one has Poison Ivy, others have had Harley Quinn). Plus, The Teen Titans, Raven, Starfire and even Beastboy and Cyborg. Yet, they are all friends here. Their futures have not been set as “heroes” and “villains” just yet.
Of course, there are villains (after all, how can you learn your superhero ways without a villain or two?) and there are the “bad boys” of another school (Lobo has a future in the band KISS I am thinking…) And this time the girls (and Beastboy and Cyborg) go out to save the city of Atlantis (which is lost again) from the evil mastermind, Brainiac! Of course, this is not just a superhero story, there are issues along for the ride, too. Bumblebee learns the true meaning of friendship and the group learns how to not judge others by the surface alone.
The artwork is very traditional flashy, modern graphic novel images, colors and action. There is some adult humor (a passenger on a cruise ship is the typical “cranky tourist”) but overall aimed at ages 7 to 10 (possibly slightly younger, and maybe up to a young 12). There are other books for the Super Hero girls as well, therefore , all ages are covered from beginning readers to the 8×8 sized books to these graphic novels to actual novels.