"That's not exactly how you expected the returning of long-lost stolen treasures to go!" No, you're telling me. This, like all the other books in this growing and growing series, has a spread of puzzles, the likes of which you will be very familiar with by the end of more than one such book. The answers to the puzzles are supposed to provide with details for the plot, and selected clues leading to the big brain test at the end. I liked the puzzles, as I always do, even if familiarity is beginning to breed something less than contentment by now. The problem here was the plot.

Yes, there is a weird fantasy world in this story, that really doesn't quite make enough sense to make this a worthwhile read. It seems to be – and forgive any mistakes caused by other people's iffy story ideas – that you have gone exploring and found an abandoned train full of stolen loot, and when you fire it up (to avoid pirates, just because) you set in motion the plan to return the treasures to the rightful owners. Later on you have to get some weird semi-Groots wet, in what counts as further evidence this creative likes making up oddball alien lifeforms.

This is a decent book in that it makes you think, but that can be said of all the volumes in this franchise. In being the weakest story-wise, and especially if you have seen sister books to this and are crying out for some novelty in the mental tasks set before you, this won't be anybody's favourite. The plot is a right hodge-podge, incoherently throwing anything and everything at the page – and hoping (in vain) that something justifies the sudoku being here. Still, for the brain training, it has to get three stars.

I really liked this. So much interactive content for maybe 6 years to 8 years. Would be a great book to take if travelling or for rainy days to keep children busy in an educational way. Children will be a learning a lot while having fun and completing the quests. A substantial number of tasks to make the book good value. Very interactive, good layout and attractive design would really appeal to lots of children.