This is the sixteenth "Parker" novel that Westlake (using the Stark pseudonym) wrote, and it was the longest at the time (about twice as long as most of the earlier ones). Parker, tired of his run of bad luck, goes back to the town where Slayground was set. There, with the help of Alan Grofield, he is intent on recovering the heist money he was forced to leave behind, hidden in an amusement park. Once in town, with the money missing, he gets involved in the local mob, and realizes that his money was used to help finance an upcoming coup.
Given the run around, and with Grofield wounded and captured by the mob (Parker is delivered one of Grofield's fingers), he calls in a group of fellow thieves (not friends, since Parker has none), and we see a reunion of sorts with many of the cast members from the previous books (including Handy Mckay, coming out of retirement after the interstate bypasses his diner). Parker decides to hit most of the money making operations that the mob controls in one night, letting his fellow crooks spilt all the money in exchange for their help in hitting the new mob boss and rescue Grofield.
When read after it was first published (1974) it must have felt like the explosive climax to the series, and for a long time it was. Westlake would not return to the character for almost 25 years. I've not read the newer books (I'm reading them in order, as we get these new University of Chicago Press editions), but leaving the character here would have been fine with me.