The set-up is straight out of a Jeffrey Archer novel. Two boys grow up in a Jewish family believing they are twin brothers, and vie for the affections of a rich girl. Except, thanks to a baby swap, they're not actually siblings at all. One is a Jew and one gentile… and it's 1920s Germany. The appalling road to the Holocaust has begun – and just in case we don't get the significance, Otto and Paulus Stengel are born on the very same day Hitler's National Socialist German Workers' party is formed in a Munich beerhouse.

The clunking exposition doesn't stop there. "What's that funny crooked cross painted on their helmets?" hisses their father a month later. "I think it's called a swastika," replies his wife – and these frequent history lessons derail the momentum in an otherwise enjoyable book. Because despite its setting, Two Brothers is good fun. There are cliffhanging moments of peril, family dramas, and Elton's stock-in-trade "cunning plans" that keep the Nazis from the door. The rich girl is actually a lot more complicated – and perhaps less deserving of the boys' love – than she at first seems: a nice twist.

An afterword reveals that elements of the narrative are inspired by Elton's family history – his father changed his name from Ehrenberg when they escaped to Britain via Czechoslovakia in 1939. Perhaps that's why he's so dutiful in endlessly detailing the facts of such a hideous time in his "most personal novel to date" – his prerogative, but the history overwhelms the characters he chooses to populate it.