Becky has a secret. She can turn herself into water.

She doesn't dare tell her parents, so she has to practise in the back garden at night.

Then she hears noises next door. Becky knows the people who live there are on holiday. So who's in their house? What are they doing?

Becky decides to check things out.

And discovers that being a superhero isn't as easy as it looks in the movies...