Action! Adventure! In a post-apocalyptic steampunk California!
There's a few hints at what caused the collapse. Aliens misnamed Martians are certainly part of it; they dropped obelisks that did something to electricity. But poison gas was also involved. But this is peripheral. Most of it revolves around the characters in a zeppelin for a daring rescue in a chilly and perpetually clouded California, and those who interact with them.
Romulus Buckle, the captain of a zeppelin he stole in a raid (retaliation for a raid that killed his sister and adoptive mother), is out to take up more forces for his clan. They are off to rescue his adoptive father Balthazar Crankshaft, captured treacherously at a parley, leaving the Crankshaft clan perilously weak for his absence.
The backstory of the world is not thickly drawn. The family's is, and the clan's, and that of those about them. Details come fast and thick and interspaced with plentiful adventure as they deal with an airborne alien monster, treat with Alchemists (whose leader was also at the parley), face robots, discover something about Romulus's adoptive sister Sabrina (Balthazar and his wife Calypso had one child born to them and eight adopted), rats that show that air is pure, Max's changing eyes (because she's half Martian), the rambunctious dog Kellie of Kells, and much more.