"They're able to transform in a second - but it becomes believable. They make it look natural," said Brooks.
"We were looking for people easily able to change their voices, mannerisms and body structure. They can do those childlike mannerisms so well - flicky and fast, and a bit whiney.
"Then they change and become stiffer and slower. It really allows them to show off the talent they have."
Peninsula is the story of 10-year-old Michael Hope, who lives on Banks Peninsula, beside an active volcano.
Thanks to a new teacher, Michael is inspired to learn his place in the world and begins mapping out his community, and capturing his surroundings through pin hole cameras - which flip images upside down.
As the volcano rumbles alongside of him, rumblings of prejudice, gossip and rumours of imminent change from the "grown-ups" threaten Michael's idyllic world.
"On one hand, it's a lovely, innocent, nostalgic story of childhood," said Brooks, who has been involved with Harlequin since 1994.
"On the other hand, you've got the darker side of human nature in the adults. It gets quite emotional when we see how adult problems affect the kids.
"And, in the end, we all have to grow up."
The setting of Peninsula is - as the playwright intended, said Brooks - sparse, with a practically bare stage and five vintage classroom chairs acting as props.
The play uses visual and sound effects to portray feelings and emotions, and the life changes the children experience.
"This is probably one of the most technical plays I've been involved in," said Brooks, who has entered Harlequin's version of Peninsula in this year's Wellington District Theatre Federation full-length play competition.
"We have a scene where the teacher shows the children how to use a pinhole camera - and we see him block out the entire classroom.
"And we see then the outside world come inside the classroom, completely turned upside down."
Brooks said the play's characters, just "ordinary New Zealanders" will appeal to audiences - and will bring back memories of their own Kiwi childhoods.
"I like working with New Zealand plays. They bring us a sense of our identity," he said.
"If you see the play, you'll see yourself - you can identify with both the children and the darker elements of adulthood.
"The play shows us our humanity: The nice and the not-so-nice."
Peninsula will be showing at Harlequin Theatre from March 20 to 29, starting at 8pm. Tickets are available from www.dashtickets.co.nz.
