Showing Painted Ladies by Robert B. Parker

Private Detective Spenser is on his easiest job yet. Art professor Ashton Prince has hired him to help recover a stolen painting. The thieves will return it in exchange for a ransom. All Spenser has to do is accompany Prince, just in case. And collect his fee.

But, as Prince walks away from the exchange towards Spenser's car carrying the wrapped painting, it explodes. Prince is gone, and with him, Spenser's cash.

Starting to investigate, Spenser discovers Prince's past is far from squeaky clean, but nothing warrants going to such unusual lengths to kill him. Who did it, and why?