BR２-02 The Double Bass Mystery

This book is mystery story. Two incident was happened. The story's character is an orchestra. They visited Barcelona to held an concert there, but one accident was happened. A member's double bass was lost. Nobody could find the double bass. The member, Penny had difficulty that she couldn't play the bass for the concert, but another member,Simon lend her his bass. He said he felt bad, so he couldn't play the bass. She could play it at the concert instead of him. Her bass wasn't find, but the concert was success. That night, second accident happened! The orchestra manager was dead and he killed by someone. The offender is Simon, and first accident is same, but why? Why he should hide Penny's double bass and kill the manager? I want you to read the climax because it is so surprised!