Cup of Blood by Jeri Westerson

I love the Crispin Guest series and have read every single one, so I was very much looking forward to this prequel.  Here we learn more about how Crispin first teams up with his sidekick Jack Tucker.  But first, a little background.

Billed as a medeival noir mystery series, her protagonist is a disgraced knight turned detective trying to make his way on the mean streets of fourteenth century London.   They call him the Tracker, because he finds things (or people), and he's pretty darn good at it too.

When a corpse turns up at his favorite tavern, Crispin begins an inquiry, but the dead man turns out to be a Knight Templar, an order thought to be extinct for 75 years, charged with protecting a certain religious relic which is now missing.  Before he can investigate, Crispin is abducted by shadowy men who are said to be minions of the French anti-pope.  Further complicating matters are two women: one from court with an enticing proposition, and another from Crispin's past, dredging up long-forgotten emotions he would rather have left behind.  And as if all that weren't enough, a cunning young cutpurse by the name of Jack Tucker has insinuated himself into Crispin's already difficult life.  The deeper Crispin probes into the murder, the more it looks like the handiwork of an old friend turned adversary.  With enemies from all sides, Crispin has his hands full in more than murder.

This is historical fiction at its best.