The Conscripted Man. The Little Shop of Wonders, #7

After trying on an authentic WW2 paratrooper's uniform--a present bought for his granddad, who's a war veteran--Christian Smith soon finds himself following in the old man's footsteps ... but for real! He's somehow transported back to Holland, 1944, hours before the start of Operation Market Garden. But that's not all. Christian has a book in his rucksack--a book his granddad lent him: The Memoirs of Field Marshal Montgomery.
And once ol' Monty gets his hands on that, you can be sure he's going to rewrite history, any way he can...