He scanned the river. The young otters had stopped playing and had scurried into the shallows. Three adults swam in circles, agitation evident in their tense posture. Their cute, cuddly appearance and playful antics camouflaged their place at the top of the Amazon food chain. Nearly six feet long, giant river otters had few natural predators except black caimans or jaguars. If the otters were on alert, the threat was likely unnatural.

In the jungle, unnatural equaled human.

Sweat dripped into his eye. He yanked a bandana from the back pocket of his nylon cargo pants and tied it around his head.

“Mac!” Behind him, Cheryl bulldozed through the rain forest. How could a woman that small make that much noise? She moved with the grace of a miniature bison. Sweat soaked the armpits of her long-sleeve safari shirt and a camera bounced around her neck.

“Shh.” Mac raised a hand, tilted his head, and listened.

Cheryl stopped and waited. Her gaze roaming the riverbanks. “I don’t hear anything.”

Mac didn’t hear as much as feel the tension in the jungle. It rippled along his skin like a swarm of ants.

Cheryl tightened the band on her ponytail. “We’ve been here for weeks. The locals are friendly. All we’ve seen are fishing boats and ecotours.”

She’d worked in São Paulo. She didn’t know jack about life in the jungle. Mac didn’t have the details, but her assignment to his team had been punishment for some infraction.

“Maybe.” He had his doubts about some of the fishing boats they’d seen. The occupants hadn’t look all that interested in the water.

Cheryl swatted at a mosquito the size of a kitten. “The biggest danger here is the bugs. Why don’t they ever bite you?”

Ignoring her complaints, Mac glanced back at the water. The otters had disappeared. Bad sign. He held up a hand to quiet his companion. “The animals know something’s up.”

“Great,” Cheryl muttered. “I had to pull the Dances With Otters assignment.”

“I am a wildlife biologist,” Mac whispered. “Now shut up so I can listen.”

The faint sputter of a motor drifted over the water. Most of the local fishing boats were man-powered. Engines were faster, but they were also expensive and required fuel. Most locals didn’t have the resources for such luxury.

An ecotour maybe?

This was a particularly dangerous region in South America, where the borders of Peru, Brazil, and Colombia converged. Drug traffickers, both large cartels and small-scale operations run by families tired of hardscrabble, subsistence living, used the river as a key method of transportation.

Cheryl went still. They both knew their university credentials satisfied villagers and officials but garnered no respect from drug traffickers.