Worlds of brutality and comic undead

Meanwhile in Brazil, Silva is asked to take charge of an investigation into the disappearance of Marta Nascimento Malan, the teenage granddaughter of Roberto Malan, a senior government official. Marta and an older girl were last seen on a beach at Recife. Marta has run away many times before. In a country rife with political corruption, Silva thinks this belated call to investigate is a cover-up to protect her powerful family’s reputation. But he feels he has to placate higher-ups. Recent newspaper articles called for his firing in the wake of a failed attempt to capture cold-blooded serial killer, Claudia Andrade, a doctor who harvested organs from scores of “living, breathing human beings.’’

The search for Marta takes him to a Manaus, a miserable town reeking of rotten fish on the banks of the Amazon, and deep into Brazil’s underworld of child prostitutes. Soon, he sees a connection between the snuff video and Marta’s disappearance, and wonders whether the missing Dr. Andrade is the woman behind the camera. He and his deputy can only hope that Marta hasn’t fallen into her hands.

This is strong stuff for strong stomachs, and giant coincidences that propel this plot are nearly eclipsed by compelling writing. Readers will smell the steam and stench of the Amazon and recoil from the torture and depredation from which Gage averts his lens, barely in time.

Lori Armstrong’s “No Mercy’’ begins with a merciless description of a youth’s body (“shriveled flaps of skin . . . [t]he crotch of the athletic shorts were ripped away . . .’’) torn apart by animal predators, cooking in the blazing South Dakota sun. From there we get flashbacks of an exhilarated Mercy Gunderson, at about the same age as the dead boy, popping the head off a living prairie dog with a single bullet while her sheriff father chuckles his approval.

Back in the present we join Mercy as she watches cows herded into a truck at the bucolic Gunderson Ranch, an operation she has just taken over after her father’s death. There are hints of Mercy’s personal burdens of family tragedies and traumatic military experiences in Iraq.