Trombone backstage

In an imaginary country, the Court Trombone Orchestra embodies the elite. Their photo is displayed everywhere, in place of the portraits of kings and presidents. Although the orchestra has fifteen members, only ten appear in the photo, as paper is particularly limited in this country. This natural, unquestionable rule means that some trombone players never appear, but their dream is to one day appear in this picture. For this, all means are good. The thirteenth Trombone, hitherto excluded, finally sees a chance to become the ninth...