Enhanced descriptions from Syndetics:

It's the middle-grade team-up of the century as the heroes of New York Times bestselling author Ben Hatke join forces to save the world in Mighty Jack and Zita the Spacegirl .

Jack and Lilly are no strangers to heroics. They've befriended dragons, battled giants, and even earned the loyalty of a goblin army. So when they meet Zita the Spacegirl, fresh from her interplanetary travels and seeking their help to face a new threat, they're more than ready for another adventure.

But the danger growing just outside the door to their world is greater than anything the new friends could have imagined. An army of giants and screeds stands ready to lay siege to Earth, determined to put the age of humans to an end.

With the gate between worlds growing weaker and time running out, can the heroes come together to save their world from their greatest enemy yet?

Reviews provided by Syndetics

Publishers Weekly Review

When vengeful giants escape their long imprisonment in the realm of Jotunheim and set their sights on conquering Earth, galaxy-roaming adventurer Zita the Spacegirl and sometime Protector of Earth Mighty Jack join forces. To overcome foes from both their pasts, the two heroes and their accompanying, ever-growing cohort of friends and allies must travel between realms, searching for a force capable of resisting the giant onslaught. The loose plot of this comic adventure serves mostly to connect the two worlds, but it's also a fun excuse to romp through various worlds and reunite characters from both series. The story's tone takes its cues from the Mighty Jack books, extending their themes of jealousy, familial responsibility, and coming-of-age, and seems more of a continuation of Jack's story than of Zita's; the main opponents are his, and he is cast as a fledgling hero while Zita enjoys a more established reputation. Retaining the humor, daring exploits, and dynamic cartooning of Hatke's previous books, the crossover is enjoyable and satisfying, if at times a tad predictable, and could serve as either a solid epilogue to both series or as the start of a new chapter in a larger shared universe. Final art not seen by PW. Ages 8-12. Agent: Judy Hansen, Hansen Literary Agency. (Sept.) © Copyright PWxyz, LLC. All rights reserved.

School Library Journal Review

Gr 4--7--In this epic crossover event, the stars of two of Hatke's previous series, Jack and Zita the Spacegirl, join forces. The book conveniently starts with a recap of their adventures thus far. With an army of angry giants bent on taking over Earth, the stakes are high. It's up to Jack, Zita, and their pals to put an end to the invasion. One of the villains says it best: "There are other human heroes at large in the scattered worlds and a spacegirl who must be stopped." The melding of the two groups of friends is entertaining, and there's realistic tension between Zita and Jack's friend Lilly, who have very different styles of tackling problems. The adults still get to play their part, albeit back on Earth. Old friends, cameos, and inside jokes make this a great volume for fans of previous installments, but even new readers will be able to follow along and will want to read the backlog once they're finished. Hatke's artwork, as usual, does a lot of the character work--he skillfully uses wordless panels where other writers might be tempted to add dialogue. The story is a bit chaotic at times since there's so much going on, but the plot is tightly constructed and keeps things moving forward. The ending is fairly emotional and leaves open the possibility of further stories. VERDICT Jack and Zita make a stunning team in this high-stakes adventure--a must for fans of both series.--Gretchen Hardin, Bee Cave Public Library, TX

Booklist Review

The gang's all here in this crossover comic, blending the stories so far started in Hatke's Zita the Space Girl and Mighty Jack series. Jack's pleased to have another superhuman kid like Zita around, and her companions get along great with Jack's friends (though it's starting to get tricky to feed everyone). Lily, on the other hand, is not convinced that Zita's all she's cracked up to be. But once giants start trying to break their way through a portal to Earth, the kid heroes will have to decide whether they can mend their friendships in time to save the world. Hatke offers up a hit parade of characters both human and otherwise, with plenty of fearsome creatures in his classic style. Bat-eared goblins, rattling skeletons, cute robots, weird aliens, serpentine dragons just about every fantastical figure makes an appearance. The action moves quickly, and readers will be better off if they're familiar with both the Mighty Jack and the Zita series, but those fans are sure to be delighted by Hatke's pages that are full to bursting with familiar faces.--Sarah Hunter Copyright 2019 Booklist

Kirkus Book Review

Heroes Jack and Zita return to meet in an epic comics crossover.In an exciting convergence between Hatke's two successful middle-grade graphic-novel series Mighty Jack and Zita the Spacegirl, the titular protagonists team up to save Earth once again. The giants from Jack's storylines along with the Screed from Zita's are determined to seize Earth for their own nefarious purposes. The heroes are flawed in ways readers will understand, and these imperfections appear to work against them: As the opposition mounts, it seems as though they may not prevail. As the action culminates in an extraordinary and unforgettable battle, they find that unity rather than force will ultimately save the day. Hatke's latest adventure is a wonderful and exciting page-turner, seamlessly blending dragons, giants, robots, and portals to other worlds, creating instant appeal for almost any young fan of graphic novels, fantasy, fairy tales, or science fiction. In an artistic style that is delightfully consistent and utterly recognizable, the illustrations are both alluring and cinematic, jumping to life off their pages through the vivid hues added by colorists Alex Campbell and Hilary Sycamore. For those who worry this may be the end of the line for their beloved heroes, fear not: Hints are left that further adventures may arise in the future. Most of the main characters present white; Jack's sister, Maddy, has autism, as readers of Jack's previous adventures will know.Perfection. (Graphic science fiction/fantasy. 7-12) Copyright Kirkus Reviews, used with permission.