This is roughly inspired by history. Jenny lind, The Swedish Nightingale, was the most famous operatic soprano of the 19th Century. In 1849 (at the age of 29) she announced her retirement. In 1850, P. T. Barnum persuaded her to tour America by promising her $1000 a night. She made about $350,000 on the tour and gave most of it to Swedish charities.
Last show of the series.
The series closes as its title vessel, The Enterprise, is all on the line based on whether Jeanne Bal as singer Julie Lang and DeForest Kelley as band musician Alex Jeffords will perform to save it. Over five years later on the first aired regular episode of Star Trek (1966), Bal would be the old flame (or a reasonable facsimile) of Kelley, then the chief medical officer on board another Enterprise (The Man Trap (1966)).