The Parade, Dave Eggers’s eighth novel, is a slim, strange book, another unpredictable chapter in the career of this hard-to-pin-down author. Like his friend and sometime collaborator Jonathan Safran Foer, there’s the sense with Eggers that, after launching himself so spectacularly onto the literary scene with his debut, A Heartbreaking Work of Staggering Genius, this is an author who hasn’t quite worked out what sort of grown-up writer he wants to be.