Aaronovitch does just keep banging stuff out to a high quality level. With this novella he expands a bit upon his American character we first encountered way back in Whispers Under Ground. Clearly, he wanted to stretch himself a bit and try on a US 'voice'. Seemed pretty successful to me but take that with a pinch of salt as I am a grumpy Scotsman. An entertaining tale of ice monsters and sins of the past coming back to haunt you. Literally. Like all Rivers output its a recommend and this one probably sneaks into the more 4.5 than 4 star territory.