Borrowed Time

I'm not exactly sure how to classify this book. Is it satire, social-economical commentary, or sci-fi?

Whatever the catagory, it's a brillant story. After picking Amy and Rory up from yet another romantic getaway, the Doctor stops at a bank on the brink of collapse. Why he thinks this would make a great stop is beyond me, but there's more going on at this bank than subprime morgages and risky stock trades. When Amy is ensared by alien technology that has led to the bank's extraordinary productivity, the stakes are raised to heart-pounding levels.

Of all the Doctor Who novels I've read, this is unquestionably the best. The moments are clear as pictures, the characterization is spot on, and there are some moments that make me cry. (Spoilers) Rory offering to take Amy's debts and making a joke about the cost, while the part where the Doctor creates a run on the bank made me want to cheer and play "I am the Doctor"

Detailed summery here