The Ghost in the Trenches. Survival through the Ages, #5

Thrust into the terrifying mud and wire of No Man's Land in 1916, 15-year-old Robert must use his modern hunting and stealth skills to navigate the lethal space between the German and Allied trenches. Moving like a ghost through the fog of the Great War, he is initially hunted as a "strange intruder" until he stumbles upon a stranded, broken-down British Mark I tank and a squad of desperate soldiers.
Using his "mechanic's brain, " Robert identifies a mechanical flaw-a simple fuel-line vapor lock or an ignition timing issue-that has stumped the early 20th-century engineers. Fixing the massive machine becomes his "bargaining chip" for survival, turning a potential prisoner into a vital asset for the small, isolated squad. As Robert keeps their mechanical warhorses running under fire, he has to out-engineer the brutal reality of industrial warfare while tracking the shimmering atmospheric "glitch" hidden behind enemy lines.
After a final, high-speed dash across the battlefield in a repaired biplane, he plunges through the anomaly and wakes up safely in his own bed in 2020.