Find out What Happened to Montaron is a side quest which can be started after you have brought the poisoned man to his friends. Xzar, a companion from Baldur's Gate will approach you and ask you to free Montaron, his fellow companion from the Harpers. Rylock, the doorman in front of the Harper building, can be found southwest in the dock district. He will ask you to kill some evil creatures in Prebek's house before he will allow you to enter the building. Go to the room with the aviary. Enter the aviary and take the Harper Bird who was once Montaron.