I love a book that starts out running and Silent Wars : Fugitives at a sprint and then goes into a full run.
We take poor Eli (a post apocalyptic cop) from an underground prison, to a freaking train fight (briefly), to a full scale invasion of Gnat territories. Think the battle of Hoth if the Empire had used mandalorians and sandworms. It’s awesome. And that’s just the opening act.
All the great characters are back and not all of them are safe. Fugitives by Adrian J Smith is the post apocalyptic thriller that you are looking for.