"The story is dramatic, emotional, humorous. It deals with such themes as the recession, depression, job loss, marriage break up and communication. It's raw and real, but it has lots of laughs and a few tears, and a happy ending. It's told through the eyes of a middle-aged couple, their kids and various friends and associates. So much of the story highlights the difference between what people are portraying versus what they are feeling. It also aims to reinforce the family unit, communication and friendship. All against the backdrop of a changing world and the challenges that come with it," he said.
With 16 cast members from around the Waikato, including Phantom of the Opera's Kersten Hickman, State Highway 48 is one of the few musicals to be written by a New Zealander.
Mr Williams said it's been a long, but fulfilling, journey.
"Note by note, song by song I made my way through it and now, five years later, I'm getting ready for the world premiere of State Highway 48."
The launch party, held on Tuesday, saw the cast perform a preview of the show which is set to run at Clarence St Theatre from July 10-12 before going nationwide.
"Broadly, I want to tell my story to a local and worldwide audience. I want them to go away fully entertained and moved but also with the feeling that they are related to the story, that some of the issues they are going through are okay, and maybe they could make some changes.
"There's lots of laughter and a few tears. It's a 21st century story. It's designed to make us feel normal, to laugh at ourselves and be happy in our skins."