This is a nice follow up to The Dark Knight Returns, save for the fact that the artwork and plot are regularly more obscure and bizarre than their brilliant predecessor. However, that said, Frank Miller remains a strong writer regardless and his ability to use Batman and the DC universe to talk about politics and craft, essentially, a beautiful dystopian novel is fantastic (and I mean that in all possible senses).
It's three years after the previous novel and Batman has been presumed dead. Of course, can anyone really kill The Batman - even Superman? Bruce Wayne may have 'died' but The Batman lives on, having trained a bunch of teenagers to fight the crime running rampant through his dystopian world - a world ruled by Lex Luthor and Brainiac, who have blackmailed Superman, Captain Marvel and Wonder Woman into fighting for them. All other heroes have been locked away or forced into other duties, so Batman makes it his job to free them and therefore free the world at any cost.
The interesting idea in this work is the idea of duty in comparison to law. The idea that the greater good must be upheld in any case is considered in this work. However, the novel almost questions: is the greater good to be observed in the near future or further down the track? It does this by contrasting two different individuals, Batman - who believes the greater good lies in helping humanity live for the future - and Superman who believes in helping humanity in the here and now, to cope with the current climates. It is the comparison between these two heroes which makes this a fascinating work of fiction and a highly readable work, if not as strong as the original.