A Bullet for Big Tom : TRUE CRIME, <i> By Michael Mewshaw (Poseidon: $19.95; 288 pp.)</i>

From “Othello” to “Wuthering Heights” to “Fatal Attraction,” romantic obsession has proven a ripe theme to propel a story, and in “True Crime,” his eighth novel, Michael Mewshaw has put it to good use.

Tom Heller Jr. is a successful, urbane crime-story writer living the good married life in Rome when word comes that his father “Big Tom” has been shot at his home in a seedy Washington, D.C., suburb.

Heller lands at Baltimore-Washington Airport to be met by his brother Buck, a two-bit criminal lawyer, and on the way to the hospital, they muse over the shooting, speculating about the culprit. Over the next several days, as Heller spends time in his rundown boyhood home, several events lead him to suspect that his father was not simply the victim of a random neighborhood assault but perhaps something larger and more sinister.

Within days, Heller’s father dies from his wounds and, at the same time, Heller reads headlines in the paper that the fabulously wealthy and influential father and son of his old college girlfriend are found suddenly and brutally slain. The next day he receives a call from the family attorney of these socialites, asking for a meeting.

In flashbacks, we learn the story of young Heller’s romance with the beautiful Elaine Yost Farinholt and how it ended in humiliation because of her father, the powerful Andrew Yost, former senator and multimillionaire, who maintained a luxurious estate at “Syms Island,” on the Chesapeake Bay near Baltimore.

The development of Heller’s 20-year-long obsession after being unceremoniously dumped by Elaine and thrown out of their Syms Island mansion is movingly enough described to rattle the skeletons of anyone who has ever felt inexplicably rejected.

Against the advice of his brother, the cops and everyone else connected with the case, Heller cannot help but try to play private detective. His journeys into this field take him from the meanest streets of Baltimore to the heights of elegance back at the Yost estate.

There are many twists and turns to the plot: Elaine is a prime suspect in the murders of her father and son; her lawyer wants Heller to help locate a mystery child that Elaine supposedly put up for adoption a quarter-century ago; someone makes an attempt on Heller’s own life; the police eventually begin to suspect Heller of some involvement in the crimes.

One of the ways to judge a good whodunit is by the number of times you think you know what’s going to happen next. If its a good whodunit, you are mostly wrong, and that is what Mewshaw has achieved here. Another way is that good mystery books are hard to review because there is so much you cannot give away for fear of spoiling the reader’s fun. This is such a book.

Mewshaw moves his story along smartly with amusing observations and anecdotes and a thoroughly knowledgeable and entertaining description of his settings in and around Baltimore.

If there is anything to cavil about it would be over the ending. As the late Walker Percy once said: “Writing a novel is like trying to lift a 500-pound fat woman--there are many things to hold up and only two hands to do it with.” Mewshaw has constructed such a problem for himself and the end result is reminiscent of that interminable last half-hour in “The Maltese Falcon” when all the characters are brought on stage to explain themselves in a carnival of explication that today no self-respecting movie director would touch with a 10-foot pole.

Looking back, however, I could not figure out how else to unravel this nest of intrigue, given all of the twigs and bits of string and paper Mewshaw had built it with. And for what it’s worth, the first two-thirds more than make up in good reading for any shortcomings at the end.