Gran and the Kidnapped Boy

Searching the witchy house, the old fish sheds and the caves-
Putting up with the bully, roller-blading Simon, and his unpleasant I'm -very -rich dad.
Following weirdly clothed Moses who carries a multi coloured shawl and a black disc that does- what?
" The village has changed!"
Avoiding wild groups who roam the Outside-
Helping a new friend to find home,-
Having power over the yacht race
-----all under the eye of granny who threatens dire punishments but is quite cool really. John, Robbie, Alex and Paul are on the move as they solve the mystery and see wrongs righted.