When cousins Joe, Tom and Pip discover that a dangerous gang of robbers is hiding in the local area, they start an investigation straight away. But hang on a sec! Granny's book club seems to be acting rather suspiciously. For one thing, they don't seem to talk much about books. And they keep going on about a local bank . . . Oh no! What if the members of the book club are the true-life bank robbers? There's only one thing for it. The cousins must stop Granny getting arrested - even if it means putting themselves in danger.