Carl is outside in his boxers trying to get his girlfriend’s cat out of a tree when everything with a roof on the planet is destroyed and the smaller number of survivors are made to compete in an intergalactic dungeon game similar to D&D. If this sounds kind of dumb, I described it correctly; it’s kind of dumb. It’s also fairly entertaining and has a good amount of heart. People who have played any sort of role playing game, like World Of Warcraft, will probably be extra amused.
There is a running joke among the fanbase that the cat (Princess Donut) is actually the main character, and Carl is just along for the ride. There’s a reason Carl’s catchphrase quickly becomes “God damn it Donut!”
Minor Early Book 1 Spoiler
Donut essentially has an Enlightenment spell cast on her, which raises her from being a regular pet to being an actual sentient dungeon crawler. She gains the ability to speak, cast spells, etc… She gets a major stat buff to go along with this. However, she maintains the haughty prissy attitude that goes along with being an award winning show cat, so her being the defacto leader of the party ends up getting them into antics because of her behavior.
Larger (but still vague) series spoilers
She does go through some pretty heavy stuff throughout the course of the series, but it’s mostly handled as if an intelligent (though naïve and impulsive) sentient character is dealing with them. She has a very solid character arc so far. There are some tough scenes throughout the series, because the dungeon is designed specifically to treat the crawlers inhumanely. But again, she’s sentient and fully capable of understanding (and planning/reacting appropriately) to what is happening around her.
Aside from that, there is also Prepotente, a goat who had the same Enlightenment thing happen to him. He isn’t introduced until several books into the series, (he is part of a different dungeon party, an entire flock of goats being led through the dungeon by his former goatherd) and he is treated like a crawler just like Donut is.
There is plenty of death and destruction, to be clear. It’s a game show designed to kill the contestants. Almost as if Squid Game were being run like a futuristic and very over-the-top Legends Of The Hidden Temple/Takeshi’s Castle. The vast majority of animal-related violence is things like NPC dungeon monsters.