They must not be read standing up, sitting down or while operating heavy machinery and should never, ever be used as a projectile.
On the other hand, if you are prepared to face dizziness, paranoid delusions or even, dare we say it, psychosis, there’s one that could be well worth the risks.
If you are feeling slightly out of kilter, then This Isn’t What It Looks Like is already working its mind-blowing magic!
The crazy, upside-down, inside-out, mysterious, madcap and fun, fun, fun Pseudonymous Bosch is back with another extraordinary, out-of-this-world chapter in his seriously addictive children’s ‘Secret Series’.
Bursting out all over with comic characters and intriguing adventures, this is his fourth book featuring the memorable Cass, Max-Ernest, Yo-Yoji and the top secret Terces Society.
Their action-packed escapades, this time involving time travel, medieval mayhem, knights, jesters, treasure, trouble, clairvoyants and comas, are the stuff of dreams for thrill-seeking youngsters.
However, not content with just telling a good tale, the ever-inventive Mr Bosch can’t stop adding some helpful, hair-raising and occasionally hilarious footnotes to keep his young readers on their toes.
Things are not running smoothly for Max-Ernest and Cass. In fact, the Terces Society’s top banana Cass is in a coma in hospital where her family are keeping vigil and the doctors desperately need to find out what happened to her.
Max-Ernest was with her when the calamity occurred but there is no way the society will allow him to reveal that it was a bite of chocolate (extra chocolatey chocolate) that put her in a coma.
It was made with the legendary Tuning Fork, the magical cooking instrument of the Aztecs, and is so powerful that the eater returns to their ancestral past.
So Cass is trapped in the past and it’s up to Max-Ernest to help her return to the present.
Meanwhile, Cass is wandering ghost-like and unseen through what looks like a Renaissance movie set where people dress in tunics and tights and sell their wares around a crowded town square.
It appears she’s on a mission to right an old wrong but if she doesn’t succeed and if Max-Ernest doesn’t manage to rescue her, the result could be catastrophic. If Cass dies, the Secret dies too.
This Isn’t What It Looks Like is top-class entertainment for kids aged 10 and over, combining comical capers with old-fashioned mystery, sparkling adventure and lashings of Bosch’s zany humour.
It’s a treat almost as tasty as one of Max-Ernest’s magical chocolate bars!
(Usborne, paperback, £5.99)