Cannibal Vengeance by Carl John Lee

Deep in the Amazon jungle, a group of missionaries are massacred by an ancient tribe. One boy escapes, and so begins a desperate fight for survival in the most inhospitable place on Earth.

Dick Ramsey is looking forward to spending Christmas with his two daughters in his isolated jungle compound. He hasn’t seen them for years. But when a mysterious stranger gatecrashes the celebration, the modern world and the Stone Age collide in a blood-drenched nightmare of gut-crunching violence.