Let's go home, Theo!

The boy Charlie lives in London in 1945 and waits for his older brother Theo to return from the war. And although Grandpa warns that Theo may have changed, it's probably not a big problem, is it? After all, everything... will work out, because Theo is loved by both Mom and Grandpa, as well as Charlie himself, and the cat Cookie!
However, the older brother returned from the front completely different. From a cheerful guy who adored his family, he has turned into a distant, cold stranger…
Soon, Charlie realizes that the wolves of war made him that way — terrible ancient beasts that devour the hearts of soldiers who have been on the front...
The boy will have to find these wolves, but how can he bring Theo's heart back if it is destroyed?