Albert Einstein Hawking Chaudhury may be the only 12-year-old boy in history to have travelled in time in the company of a prehistoric tortoise and a hamster named Alan. It’s the result of being in possession of a time machine, which once saved his father’s life but now unfortunately finds him trapped in a cave sometime in the Cretaceous period, ‘being eyed up as potential lunch by a family of dinosaurs’. He has a lot of explaining to do in Time Travelling with a Tortoise by Ross Welford, a hair-raising and ingenious adventure in the multiverse.

‘None of it’s my fault,’ Al says, although that doesn’t seem to be the view of his companions, Carly and Paulie, who have found themselves transported back in time with him in a purple tuk-tuk (the tuk-tuk plays a significant role in this story, as does its owner, Al’s sage-like Grandpa Byron).

Cowering in the cave, they are terrified to be confronted by mummy dinosaur’s huge amber eye peering in at them. It occurs to Al that if he reached out, he could fit his whole fist in her ‘moist, steaming nostril.’ Cue the three of them clutching each other in terror and Carly and Paulie, being particularly baffled by events, demanding some answers.

And here’s where it gets super-clever. Fans of Welford will know that this book is a sequel, set three weeks after Al’s first adventure, Time Travelling with a Hamster. In the first book, Al saves his father’s life and therefore changes the course of history. In this marvellous stand-alone sequel, he must deal with the consequences of meddling with time and not paying attention to detail.

A thrilling and brain-stretching read. Top tip: remember to keep an eye on the tortoise.

If you like this, see The 1,000 Year Old Boy by Ross Welford.

Time Travelling with a Tortoise by Ross Welford is published by Harper Collins, 272 pages.