The Box boys and the magic shell - Jenny Nimmo

The Box Boys aren't brothers, but they were born on the same day in the same year.and they have the same surname! And when they get together, John and Scott Box always find adventure of a magical kind . . .

John is woken one night by the sound of someone softly calling his name, and he searches the house to find out who it is. When he discovers the conch shell that his Uncle Vince brought back from his travels, John can't believe it - but the shell is really calling to him. The shell wants to go back where she belongs - to the sea. The next day, John and Scott set off the for the seaside, but will they make it in time . . .