Tabernacle Choir Aliens

The Tabernacle Choir at Temple Square, formerly known as the Mormon Tabernacle Choir, provided the longest-running music broadcast in Earth's history. Widely regarded as the epitome of the planet's choirs, tickets to the annual 24th of July celebration were increasingly hard to acquire. Security technology on this backward planet evolved to the point that stealthy visitations by extraterrestrials was about to become impossible. Which threatened to disclose the extra-terrestrial members of the choir.