Simple survival. They attempt to cross the United States to reach a safe haven in Alaska.

The debut issue introduces the central theme of survival at any cost through two parallel timelines: the immediate aftermath of the outbreak and the present day, ten months later. The Outbreak (C-Day)

Squidward: (sighs) I was having such a nice practice session...

The first volume (Issues 0–9) is widely considered the strongest entry in the franchise. Exploring CROSSED - Page Chewing

If you meant a specific issue or spin-off (e.g., Crossed: Badlands #1), let me know and I can refine the answer.

To understand , you must first understand the rules of its universe. Unlike zombies (slow or fast), the "Crossed" are not mindless. They are infected by a pathogen (airborne, bloodborne—the ambiguity adds to the terror) that strips away every layer of human empathy, conscience, and restraint.