The butler did it. With that matter aside, the plot of "The Last Innocent Man" bears no elaboration. It may be that murder mysteries can only be judged as good or worth reading in direct relationship to the extent that the unraveling of the skein surprises the reader. Phillip M. Margolin's second mystery has some of those surprises in store for its reader. But apart from its corkscrew plot, there is no particular literacy merit in the novel.

In the shadow of this conventional whodunit, however, are two themes worthy of consideration. Both have to do with lawyers and lawyering. The first is an ethical reflection; the second, a social reflection.

Margolin, himself a criminal lawyer, has chosen as protagonist David Nash, a criminal lawyer, young, energetic and highly respected. Nash has successfully defended many individuals accused of loathsome crimes and we find him rudderless and tired of letting the animals out of their cages and tired of justifying his action by the use of philosophical arguments he no longer believed in." Through Nash, Margolin presents in different ways throughout his novel one of the most difficult ethical dilemmas in our jurisprudence. How can a lawyer defend someone he believes to be guilty? For a lawyer, this question is a kind of mnemonic device for dredging up that first essential excitement of learning about the law. That rush of learning brings back to mind these concepts:

If you as a lawyer refuse to defend a person charged with a crime, based on your assessment of the charge or the defense, you become in effect the judge.

An argument which may not convince you as an accused person's lawyer may yet convince a judge or jury, and if the argument succeeds, then the judge is right and you are wrong.

An accused person's rights are determined by the judge and jury, not by his lawyer. You must advise your client about the probable outcome of a criminal trial, and may do so with some vehemence, but you must not impose your conclusions upon your client.

Even if the accused has "done it," he may not be guilty by virtue of some legal defense, such as self-defense, lack of criminal intent or temporary insanity. However, if you "know" the defendant is guilty of the offense with which he is charged, and he tells you, then you have other obligations. You can't put forward a case you know to be false. All you are permitted to do is allow your client to enter a plea of not guilty and challenge the prosecution to prove its case. You can then challenge that case with every permissible device, and there is nothing improper in fighting to demonstrate that the prosecution's evidence has fallen short of proof beyond a reasonable doubt. This is entirely different from putting forth a defense known to be false.

Nonlawyers as well as lawyers have been fascinated by these ratiocinations, and Margolin's book, while it does not deal with these topics on scholarly terms, stimulates us repeatedly to think about them. The book will draw lay people into the complexities of these perennial criminal law questions, even those impatient with lawyers (and judges) who obtain acquittals for defendants who have "done it." Margolin's presentation of these ethical questions gives substance to a novel otherwise noteworthy only for its conjuring.

His jampacked plot also shows his perception of lawyers in our society in a fairly sober way. Unlike some, this novel about lawyers and the legal system is not designed to have its author nominated as Chairman of the National Committee to Horsewhip Earl Warren and All Lawyers. Nor is it an apologia. Our hero is presented simultaneously as hard-working and bright, unethical and a murderer, but eminently human and sympathetic. He has an affair with and then falls in love with (ah, even a few short years ago only the reverse would have been presentable) the wife of the novel's principal defendant, and the personal and professional complications that liaison creates are legion.

Margolin is neither harsh nor soft. He shows us in this superficial novel the difficulties of lawyers as people practicing in a system of justice which is the same for the guilty and the innocent. To his credit, he sets his presentation of the formal duties of lawyers in the system against the ambiguities of human relationships -- and exposes the costs paid by a conscientious lawyer in the coin of human feeling.