Song (Overture)

Though it was thought of as having Romanian Gypsy origins, a song was actually accidentally brought through the Cardiff Rift by an unnamed species. It became infamous on Earth for making everyone who sang it commit suicide.

When a nightclub singer sang the song on the night of 7 August 1941, "sleepers" of the unnamed species awoke and began attacking everyone in sight. After leading them into the Torchwood Hub, Jack Harkness' singing of the song — which was, according to the Commodore pitch-perfect — made the aliens explode through sonic power, leaving nothing but pools of blood.

Its lyrics included:

Sorrow of Monday

In darkness, I thought of you

My soul alone decides to take the journey,

And soon they'll be tears.

(COMIC: Overture)

Behind the scenes

This song was clearly heavily inspired by the real world song Gloomy Sunday, and, more specifically, the urban legends surrounding it and its power to drive people to suicide due to its extremely melancholy tune and lyrics. The details given of the song in-universe (minus of course the supposed extraterrestrial origin) also fit with this. However, the actual lyrics of the song given in the story do not correspond with the real world ones, so it cannot be said to refer to the same song in-universe.