The Falcon’s Malteser by Anthony Horowitz is the first of 8 novels in The Diamond Brothers series, which tells the adventures of the world’s worst private detective.
Set in London, it features Nick Simple and his older brother Herbert (who works under the name ‘Tim Diamond’ because he thought it sounded better). As this group of lessons covers, they’re approached by Johnny Naples who employs them to look after a box of chocolates. It contains all the staples of a good detective story - mystery, intrigue, arrests, nightclub singers, shady figures, kidnappings and diamonds.
The story has also been adapted into a stage play and a film called Diamond’s Edge or Just Ask for Diamond, depending on where you live.
Here is a promo that was created for New Old Friends for their stage production of the story.
And this is a section of the film that matches the passages we're looking at in these lessons!