THE EMPTY ENVELOPE Dink keeps getting letters addressed to D. Duncan, but when he opens them they all start 'Dear Doris' and don't make any sense! Josh and Ruth Rose thinks someone's playing a trick on Dink, but Dink is sure there's more to it than that - especially after Doris Duncan turns up demanding her letters! What's so special about these envelopes? And will the gang be able to uncover the truth.