They're somehow all connected to the collapse of a good noble house in Baldur's Gate, the now destroyed House Fonster.
Were hired by Flaming Fist to investigate the Cult Of The Dead three. This led them to the Elfsong Tavern then later a Bathhouse across the city. Underneath said bathhouse there were sewers containing the cultists. A hidden passage revealed secret chambers with the leader.
They teamed up with Mortlock to take him down and after agreed to bunch the ever living fuck out of his brother, Amrik