Harold and the Mermaid: A Harold and Charlie adventure story

When Harold and Charlie go on holiday all Harold wants to do is go searching for a mermaid rather than teach Charlie how to swim.

All goes well until Charlie starts flying a kite and gets blown off the boat and into the water.
Can Harold save Charlie before he sinks too deep?
And who is the mysterious lady who comes in to the rescue? Could it really be a mermaid?