Characters -- and writers -- in peril

The Mayday
By Bill Eidson
Justin, Charles, 310 pp., $24.95

Alone
By Lisa Gardner
Bantam, 324 pp., $24

A Window in Copacabana
By Luiz Alfredo Garcia-Roza
Translated, from the Portuguese, by Benjamin Moser
Holt, 256 pp., $23

Threaten helpless innocents -- it's a tried-and-true plot device designed to make the reader care. But writer beware: It has the power and peril of a third rail.

Jack Merchant, a tough and taciturn ex-DEA agent who is trying to live down past mistakes, is on a quest to save a pair of children in Bill Eidson's ''The Mayday." The tale begins with a distress call. Matt Coulter's dream of sailing across the Atlantic with his family on his 38-foot sloop, Seagull, turns into a nightmare in heavy seas off the coast of Rhode Island. He watches in horror as the mast breaks: ''The mast was like a living, angry thing, gouging the deck where he had been kneeling." The boat founders. Coulter, his wife, and his two children are set adrift in a lifeboat.

Coulter wakes up in a hospital, days later. His wife has been found dead; Seagull is presumed to have sunk. Coulter insists that a boat responded to their distress call, and that his children were captured and taken on board. Police dismiss his claims as the delusions of a guilt-ridden father.

Coulter turns to repo contractor Sarah Ballard to find his boat. Ballard is a tough young broad who's made it in a man's world. She's sympathetic to Coulter's pleas, and brings him to Merchant, who works for her.

''Listen to him. And be nice," she tells Merchant. ''He's lost his family." He listens, and warily agrees to investigate.

In this second series novel from a local veteran thriller writer, there's plenty of sexual tension and easygoing banter between Ballard and Merchant. The kids -- rebellious 12-year-old Sean and naïve 7-year-old Laurie -- are sympathetic and genuine. Their plight lends urgency to Merchant's quest to free them from the clutches of a nasty villain driven by greed and hubris. Eidson is in the zone when he writes about sailing and diving, and the sea itself is one of the book's most vivid characters.

Four-year-old Nathan Gagnon is at the center of the maelstrom in Lisa Gardner's ''Alone," one of the bloodier thrillers I've read in a while. By the end, 10 people have been murdered, and one is in a coma.

Nathan's condition has been labeled ''failure to thrive" by doctors who are stumped for another medical term that accounts for his lethargy, stunted growth, and attacks of pancreatitis. He's got the family from hell: an abusive father, Jimmy; an emotionally frigid femme fatale mother, Catherine; and a bullying paternal grandfather, Judge Gagnon.

In the opening scene, Nathan watches his father getting blown away by police sniper Bobby Dodge, a member of an elite Massachusetts State Police SWAT team. Bobby is racked with guilt that Nathan witnessed his father's shooting, though he's convinced that he acted just in time to prevent Jimmy from killing his wife.

To Bobby's superiors, it doesn't look that clear-cut, and Bobby finds himself temporarily relieved of duty. Catherine Gagnon casts a spell over him. He risks his job and reputation to protect her from ruthless Judge Gagnon, who claims Catherine engineered Jimmy's death and is deliberately making Nathan sick, and from a demon unleashed from Catherine's past -- a child molester and serial killer.

Though many readers will enjoy this novel's thrill-packed, roller-coaster ride, I found myself disturbed by that little boy, sick and listless throughout the novel, more prop than character, and by how Gardner uses his vulnerability to sustain the plot.

Brazilian author Luiz Alfredo Garcia-Roza puts a not-so-helpless damsel in danger in ''A Window in Copacabana," a taut police procedural set in a Rio de Janeiro so hot that the ''wet burden of sweat clung to the body like the cold skin of a reptile."

Three on-the-take police officers in Chief Inspector Espinosa's precinct are murdered, caught off guard by a killer who dispatches them in plain view and leaves behind no evidence or witnesses. The mistresses of two of the murdered men are killed before investigators can interrogate them. Celeste, the mistress of the third murdered officer, flees, and the novel turns into a race to keep her from becoming the next victim.

When the officers in the precinct circle the wagons, refusing to share what they know, Espinosa launches a covert investigation. He wonders if it's a case of ''one bad apple, killing others."

Then Serena, a wealthy government official's wife with too much time on her hands, gazes out her high-rise apartment window and sees a man and a woman arguing in an apartment across the street. Moments later, the woman plunges to her death. Serena becomes obsessed with this mysterious death, but the investigators dismiss her contention that it was murder. When a connection between the victim and the missing mistress is established, Serena gets Espinosa's attention.

This fourth Inspector Espinosa novel is about corruption and greed, and the choices people make that doom or safeguard them. Originally published in Portuguese, the writing is spare and lean, as is Espinosa -- a gritty, appealing, pragmatic man with an appreciation for a pretty woman. A surprising plot twist provides a satisfying ending to an engrossing novel.

Hallie Ephron is co-author of the Dr. Peter Zak series of psychological mystery thrillers by G. H. Ephron.