Skin game - Jim Butcher

Harry Dresden, Chicago's only professional wizard, is about to have a
very bad day. As Winter Knight to the Queen of Air and Darkness, Harry
never knows what the scheming Mab might want him to do. Usually, it's
something awful.

This time, it's worse than that. Mab's involved
Harry in a smash-and-grab heist run by one of his most despised enemies to recover the literal Holy Grail from the vaults of the greatest
treasure horde in the world - which belongs to the one and only Hades,
Lord of the Underworld.

Dresden's always been tricky, but he's going
to have to up his backstabbing game to survive this mess - assuming his
own allies don't end up killing him before his enemies get the chance . .
.