I decided to go back to the beginning and read The First Deadly Sin and was pleasantly surprised. Lawrence Sanders was on a creative roll with this book. The book opened with a section dedicated to Daniel Blank, the serial killer whom Delaney is forced to pursue and begins to explore his character. We do not see a murder until a few chapters later. Sanders then switches to a section dedicated to Delaney and continues moving between Blank and Delaney as circumstances and the investigation bring them closer to each other. There are only hints of Delaney's weakness for sandwiches, unlike the remaining books in the series that devote time and pages to the different sandwiches he makes for himself. The ending of the book is unlike that of the movie (which, for me, was tonally more appropriate) and, in addition to offering geographical closure (we begin and end the book at Devil's Needle with Blank) also offers food for thought if you are looking for allegories. The police procedural got its due but Sanders also found time and space to tell us more about both Daniel Blank and Edward X. Delaney. Cop and Killer often seem like "doubles" and Delaney needs to think like Blank in order to try and understand him and his killings.
I turned my attention to The Second Deadly Sin and began to see patterns, some of which made me uneasy. I started getting the feeling that Sanders either lost the creative muse that fuelled The First Deadly Sin or had managed to pick a leaf from the assembly-line writing of Sidney Sheldon. The book opened with a murder, just like The Fourth Deadly Sin and, again just like the The Fourth Deadly Sin,it was clearly committed by someone whom the victim knew well. Everything else until the revelation of the killer's identity is an engaging exploration of Delaney, his familiar battle with departmental politics, his almost secretarial approach to detective work and more sandwiches. The book was a satisfying page-turner, but offered nothing else, unlike its predecessor.
I just finished The Third Deadly Sin yesterday and the feeling that Sanders had run out of gas got even stronger. The book opens like The First Deadly Sin by introducing us to the killer, but Sanders does not seem interested any longer in giving Zoe Koehler as much room as he did Daniel Blank. The first chapter ends with a murder just like the second and fourth editions in the series. The second chapter opens with Edward X. Delaney and his sandwiches and also makes this book structurally similar to The First Deadly Sin as we switch between Zoe Koehler and Delaney's investigation. Once again, we see Delaney dealing with the idea of the killer being a woman, but he does not seem as interested in understanding her as he was when trying to track Daniel Blank down. Sanders tries something different by having Delaney and his wife argue about women's liberation -- it doesn't help that the killer, who suffers from the rare Addison's disease, embarks upon these killings when she deals with the crimson curse. It's a pity that he does not choose to explore the idea of blood-letting and the nosebleed in Australia. Sanders seems to have instead dedicated his time to churning out a bestseller. As things move to a conclusion, the writing gets sloppy. We get expository dates and times that insult our intelligence. The novel also ends with geographical closure (Zoe's apartment) in tribute to the first book, but in a more tonally sound fashion.
After having read all four, I can see why Sanders never got around to writing any more. I would like to think that he just never got an idea that would justify an entire book offering something more than the now-familiar tropes (Delaney getting pulled out of retirement, Delaney's sandwiches, Delaney's notions of crime and punishment -- the Dostoyevskyian angle appeared in the first book and never came up again). If I had to rank the books starting with the one I liked most and ending with the one I liked the least, I'd choose The First Deadly Sin to head the list, followed by The Third Deadly Sin (I have a weakness for serial killers and books where I don't have to sit and wait for a "grand revelation"), The Second Deadly Sin and The Fourth Deadly Sin (being a weak shadow of the second book).