Sometimes I feel just like the glass in my fish tank—people look right through me.

Twelve-year-old Tilly dreams of becoming a marine scientist, but she doesn't even own a swimsuit. She lives in a drought-stricken town with her mum and younger brother Oliver, who is autistic.

Oliver's meltdowns are making life unbearable. He needs so many different kinds of therapy that there's never any time—or money—left over for swimming lessons. Tilly knows Oliver's needs have to come first, but it's hard feeling invisible all the time.

When Mum announces they are moving to the Queensland coast, Tilly is excited at the thought of finally learning to swim—even snorkel! But she is also worried. The thing about Oliver is, he can't cope with even the tiniest of changes to his routine.

It isn't long before the cracks begin to show. Could so many changes all at once threaten to shatter the whole family?