It’s just a little key. Somebody sent it in the mail.  But the person it  was sent to never got it – and nobody knows who sent it. So now it's in the  Dead Letter Office at the city post office.When Danny hears about it, he  decides to solve the "BIG mystery of the LITTLE key. "Danny  and his friend Emma search for answers all over town.Who sent the key? Who was  it for? And, most importantly, what does it open?
  Special Features: Robin Readers is an exciting series of original  fiction for learners  of English. Designed to be read for enjoyment, the stories are accessible and  engaging, with carefully graded language.
  Each reader comes with  comprehension and vocabulary activities to consolidate understanding. More  difficult or uncommon words appear in a glossary.
  There is a stimulating variety of settings and  storylines across a range of genres, including travel adventures, fantasies, science fiction and thrillers.