Black Hand Shanty

Description
Sing, sing to the broken road, Paved in the oaths of forgotten men, And blood and bones that churned the sand, The bitter heart of a traitors den.

Behold the swollen corpses song, Croaked from the throats of hanging fools, Pattering feet in a rictus jig, Come to the rope our eager ghouls!

Listen now to the wind swung souls, Diving down to the rocks and sand, Holding their tongues in bloat and decay, Never again to cross The Black Hand.

Source
The note is a random drop from Black Hand NPCs.