Written by George Mann, Engines of War concerns the events preceding Day of the Doctor (from the War Doctor's perspective), and is....well, it's a heckuva ride. Many fans cite the Virgin New Adventures as being "adult Who" (If you're curious about Doctor Who in book form, might I suggest The Doctor Who Book Club Podcast?), but Engines of War really is mature without being pretentious about it. The Doctor (or, as the Daleks refer to him, "The Predator") finds that the Daleks have a superweapon, and are planning a last ditch effort to end the Time War....
....which, of course, the Doctor decides to end by warning the Time Lords. However - and this is Mann's masterstroke - we see a civilization that is, as the Sixth Doctor might put it, "decadent, corrupt, and rotten to the core." One of Mann's deft touches is how he suggests this corruption - as well as the nature of the Time War - in simple yet disturbing terms. (There is no overt gore, but some of the more terrifying elements would not be out of place in a Hinchcliffe/Holmes production). With a one-off companion named Cinder (who actually made it into the Doctor Who: Legacy mobile game), the War Doctor actually is much more Doctor-like than we've seen. (Of course, there's also some added ruthlessness and crankiness - after all, this is a man who refuses to refer to himself as the Doctor). But one of the great things about Doctor Who: Engines of War is that it provides a strong read and a unique take on the Doctor - so much so that I wish this were "canon".
(It's actually so good, I'll be checking out some of Mann's other, non-Who work. If he can handle a franchise this well, I can only imagine how he would handle his own creations....)
It's going to be a long wait until Series Nine in August/September....so one good way to ease the wait is to pick up Doctor Who: Engines of War. You'll thank me later.