Turn Coat

Turn Coat is the eleventh installment in the series, published in April 2009. The following blurb is taken from www.jim-butcher.com:

The Warden Morgan has been accused of treason against the Wizards of the White Council — and there's only one, final punishment for that crime. He's on the run, wants his name cleared, and needs someone with a knack for backing the underdog. Someone like Harry Dresden.

Now, Harry must uncover a traitor within the Council, keep a less-than-agreeable Morgan under wraps, and avoid coming under scrutiny himself. And a single mistake may cost someone his head — someone like Harry.