Enid Blyton <br/><br/>
The Adventure Of The Secret Necklace 

<br/><br/> When Bob and Mary arrive at their Granny's for the summer holidays they are delighted. But this year their big, rough cousin Ralph is staying as well. One rainy day, Granny tells them about a beautiful necklace that disappeared 100 years ago, and soon Bob and Mary find a secret passage.<br/> 
<br/><br/><label>ISBN: </label>9780747532118 
<br/><br/><label>Dewey Class. No.: </label>Eng BLY