The research paper examines the author’s participation in the original production of the a cappella musical Watu Fangta, with a focus on the analysis of musical composition. A cappella music features vocal beauty and techniques, while musical theatre stresses storytelling skills. The author combined the best of both elements in an effort to overcome difficulties in the application of a cappella music in musical production, writing a full a cappella musical. This paper comprises four chapters. The first chapter explains the author’s motive for and concept behind musical composition. The second chapter breaks down the book and song structures, and illustrates how each scene and lyrics play a crucial role in the composition of melody, mood setting, and texture. Chapter Three analyzes the motifs, themes and vocal arrangements in each song. In the final chapter, the author shares thoughts on the production and rehearsal process, and offers suggestions for future musical composers.