Angelic little babies make idiots of us all. A pregnant, unmarried grocery store clerk named Agatha dotes on her unborn child in THE SECRETS SHE KEEPS (Scribner, $26), Michael Robotham’s insightful psychological thriller about the joys and fears of impending motherhood. Agatha is consumed by all things prenatal, and especially the pregnancy of Meghan, a well-off and beautifully turned-out married customer, also in her third trimester, who represents perfection to a woman whose absent boyfriend wants no part of fatherhood. Dreaming of a future life when she and Meghan have become friends, Agatha makes plans: “We’ll do yoga classes and swap recipes and meet for coffee every Friday morning with our mothers’ group.”

When Agatha and Meghan, who alternate as narrators, realize that their due dates both fall in December, a bond is forged. Meghan welcomes Agatha into her home and invites the kind of intimate exchanges she’ll come to regret when her new acquaintance turns out to be a stalker. “I know her timetable, her friends, her habits and the rhythm of her life,” Agatha says proudly. But if Agatha isn’t as innocent as Meghan thinks, Meghan isn’t as wonderful as Agatha fantasizes. Both women, in fact, are clutching secrets that can ruin friendships, destroy marriages and shatter lives.

Agatha is the more interesting character, with her harrowing history and desperate yearning for a child to heal the wounds of past traumas. Her neediness may be fanatical and her assumptions psychotic, but her suffering is real. And she’s still bitter about mothers who thoughtlessly assume that some women are simply “too selfish or too choosy” to have children. But beneath the chattiness of her parenting blog, “Mucky Kids,” Meghan’s uneasy narrative voice registers her fears for her newborn son and her own private qualms. “I am a cliché,” she admits. “My blog sums up my existence — safe, uncontentious, and shallow.” Both women are extremely articulate, but when the plot takes an unspeakable turn, they’re no longer able to hide behind words.

Of all the places where you really do not want to come across a couple of nut cases with guns, a zoo full of wild animals would be high on the list. Gin Phillips taps into that primal fear with FIERCE KINGDOM (Viking, $25), a heart-thumping thriller about a mother who finds herself and her 4-year-old son trapped when two marksmen start hunting down visitors. Joan is about to leave the park with Lincoln, a dear child who entertains himself by reciting college football chants, when the sound of shots sends her backtracking into the deeper parts of the zoo.

Phillips dutifully sketches out a back story for the gunmen, but once Joan’s maternal instincts kick in, she summons her survival skills, and the thrust of the narrative turns to her nerve-plucking race for safety, past “wild things in boxes.” Packing 40 pounds of human cub on her hip, she sprints from one habitat to the next and in the face of unexpected danger gives new meaning to the term “tiger mom.” Compressed into a little over three hours, the story flies by like a gazelle being chased by a lion and is easily consumed in a single sitting.

Victorian ladies in distress always consult Sherlock Holmes. Their plebeian sisters must settle for the seedy sleuth in Mick Finlay’s first mystery, ARROWOOD (Mira, paperback, $15.99), who lives in a squalid district of South London and caters to clients like Miss Caroline Cousture, whose brother has disappeared from his kitchen job at the Barrel of Beef chophouse. William Arrowood is a Falstaffian fellow who lives behind a pudding shop and prides himself on being “an emotional agent, not a deductive agent,” like his famous nemesis. “I see people,” he boasts. “I see into their souls.” His assistant, Norman Barnett, is content to study the filthy streets teeming with “night-time people” who “stagger and shriek,” blind with drink and despair. Gin is both medicine and religion for many of these slum dwellers, who privately believe that Jack the Ripper is “God’s punishment for the drink.”

Wouldn’t a hairdresser know not to take a hair dryer into the bathtub? That’s not the only thing fishy about the death of Lorna Belling, whose husband and lover are equally horrid in NEED YOU DEAD (Macmillan,$27.95), the latest mystery in a scrupulously maintained procedural series by Peter James. And of course, Detective Superintendent Roy Grace, a decent and damned attractive senior officer with the Sussex Police, is too shrewd to write off Lorna’s death as a classic domestic abuse case.

Despite the glaringly obvious clues pointing to her jealous husband, no Roy Grace mystery can be resolved without one of the detective’s intense interviews, which he compares to “games of poker,” having perfected the fine art of bluffing, along with the unnerving skill of reading a subject’s body language. But he may have met his match in 10-year-old Bruno, the son he never knew he had until his first wife broke the news posthumously in a suicide note. Grace is a detective known for his human touch, but a moody little boy may prove to be his toughest challenge.