[This will be the last of my opinionated posts on my previously unstated (and unexamined) expectations for manuscripts in each of the subgenres of crime fiction....]
At the opposite end of the spectrum from the amateur sleuth is, of course, the professional sleuth. I put the professional sleuth in a different category than the police sleuth. For example, many of the great English detectives (currently being written about) are all in the employment of the crown, officially, as policepeople, so I wouldn't classify them as professional sleuths--that is, those who are self-employed investigators. Lynley is a police (as Martin Amis would say); so are Dalgliesh and Wexford, and Dalziel and Pascoe, and Inspector Morse.
In the States, where living in that borderline between legal and illegal seems to be more appealing to the reading public, we have more private P.I.s. We have Easy Rawlins, and Kinsey Millhone, and (until recently) Spenser. Really, there's no better job for someone who isn't afraid of a little danger, doesn't want a boss, is notoriously afraid of commitment to the opposite sex, and doesn't mind walking that provocative line between legal and illegal. In fact, I think this last point is one of the reasons why we like P.I.'s so much in the States. Policefolk have their hands tied in terms of exacting poetic justice, but P.I.'s can be so much more creative.
I'm not seeing as many professional P.I. manuscripts as I used to - interestingly, the ones I do see tend to be written by people who are, ahem, a bit older - but I still think there's a market out there. So, herewith my suggestions for writing a marketable P.I. book.
1. YOUR SLEUTH ISN'T AN AMATEUR, SO DON'T TREAT HIM/HER LIKE ONE. Amateur sleuths really don't know what they're getting themselves into most of the time, and that's half the fun. But professional sleuths do, and they should proceed accordingly. The nice thing about a pro (from the writer's perspective, that is), is the fact that s/he can't cherrypick assignments if s/he wants to pay the rent and eat. This allows you to get your sleuth involved in all sorts of fun and nasty situations. However, even the most unseasoned sleuth is neither stupid nor suicidal. Experienced P.I.'s know when to walk away from a case, and when not take one. So your set-up has to make sense, which means that some deception on the case giver's part is often necessary.
2. CONNECT, BABY, CONNECT. The professional sleuth gets the job done by having a wide variety of contacts, both legal (read: in the police, forensics, and M.E. departments) and shady (think various street types, a la Mouse in the Mosely books). What I find in many books is the fact that these connections are taken for granted, and yet they are often a one-way street. By that I mean, the P.I. often goes to his contacts for information, but rarely gives anything in return. In the early books of a series, I'd like to know how these contacts developed and what keeps them going. Of course, I don't need major backstory on each, as that would slow the book down, but I do want to know something. And I want those contacts, especially the seedy ones, calling in favors once in a while.
3. CARRY A PIECE. It never makes sense to have a P.I. who doesn't carry some sort of weapon for self-defense. I wouldn't necessarily make my P.I. an expert in everything from archery through intercontinental ballistic missiles, but I would make sure s/he has some facility with a gun, a knife, a rope, and perhaps even one of the martial arts. That said, P.I.'s are not the descendants of Superman and Wonder Woman, and they can be outnumbered, outgunned, or outwitted. Smart villains (and we all like a smart villain) know this and plan accordingly.
4. THIS AIN'T NO COZY. The hardboiled is a good place for cynicism; so too is the professional P.I. book. Experienced P.I.'s have seen it all and really aren't given to sunny interpretations of people or situations. They are almost never naive, and that includes matters of the heart. Oh, how often I see that Macho Tough Guy or Facho Tough Gal taken in by that sweet-taking babe or Lothario; and oh, how often I want to scream that cynics are no less cynical about the opposite sex than about life on the streets. A good professional P.I. assumes the worst and is usually right; even when s/he's wrong, there's usually more to the story that only confirms the P.I.'s generic cynicism. This isn't to say that the P.I. can't have friends and relationships (though many writers choose to make the P.I. a loner, which is the lazy writer's way out). But it is to say that P.I.'s trust most people only about 20%, and trust the people they love the most only about 50%. This comes not from an inborn dark view of the world but rather experience and observation. And let us never forget that cynics are almost always frustrated idealists.
5. STAY ONE STEP AHEAD. People hire private detectives because they want somebody smart, someone with a track record of getting the information or getting to the heart of the matter. This means that creating an effective sleuth requires superb plotting skills in which the sleuth, while hiding some information from the reader, manages to anticipate what the bad guys are going to do. PLEASE! Note that "hunches" are the completely bogus and inane crutch of unskilled crime writers. If you must have a hunch, please explain where it comes from. Has the P.I. encountered this situation before? Does it remind her of the way her sister used to behave? Did she once see it on an episode of CSI? Has he pieced this pattern together based on experience in interrogating suspects?
6. A RIVAL IS MOST ENJOYABLE. I love when a P.I. (or any protagonist, for that matter) has a rival who occasionally bests him or her. Maybe it's a friend with whom the P.I. has a friendly rivalry or history of one-upsmanship. Maybe it's an enemy for whom the P.I. has a grudging respect. The occasional intrusion of this rival into the proceedings can be great fun and force the P.I. into ever more subtle and brilliant machinations. Of course, our P.I. can't always win, otherwise we as readers would grow weary of the rival. So it's nice to have the rival occasionally win out over our P.I., to encourage our protags to be their best. I recently heard the term "frienemy" used to describe the type of person with whom we are ostensibly friends, but who remain rivals or foils to us, and I love it. Rare is the P.I. who couldn't benefit from a frienemy's taunts.