Always a Thief (Quinn/Thief #2) by Kay Hooper

The priceless, rarely displayed Bannister collection is about to be exhibited-- and the show' s director, Morgan West, can' t ignore her growing uneasiness. She' s certain she hasn' t seen the last of the infamous cat burglar Quinn. But she never expected him to turn up at her apartment one dark night in desperate need of her help-- help she can' t refuse. The mysterious master thief is playing a dangerous game, and it' s a game that just might get him killed.
With Morgan' s help, Quinn sets a trap intended to catch someone far more elusive... and more deadly... than a thief. But an unseen threat shadows him in the fog-shrouded San Francisco night, an unknown adversary more cunning than any he has yet encountered. Now, just when the stakes are higher than even Quinn can imagine, no one can be trusted-- and everything' s at risk.