Logline
An accident with an experimental quantum probability field causes everyone on the USS Enterprise to break uncontrollably into song, but the real danger is that the field is expanding and beginning to impact other ships—allies and enemies alike.
Written by Dana Horgan & Bill Wolkoff
Directed by Dermott Downs
The three Klingon vessels that got rekt by V'Ger at the beginning of TMP were K'Tinga class ships. That was less than 20 years after this episode was set. However, the K'Tingas did remain in service well into the 24th century, likely for the same in- and out-of-universe reasons that the Excelsior class did.