In Skull & Bones, Telok Penjara is a pirate den just like Sainte-Anne. In this settlement, you will find the same NPC as the first pirate den. You will get better blueprints of various items such as furniture and weapons. You will also find the blueprint to craft the Padewakang ship.
To reach this location you need to go toward the northeast side of the map as shown in the image above. Below you will find a brief walkthrough to find all the clues and complete the A Legacy of Madness investigation.
Skull & Bones A Legacy of Madness Telok Penjara Location
While exploring various outposts you might find some NPC whispering, going near them will show a prompt to bribe with some silver coins in exchange for information. Upon hearing a rumor or information, you can start an investigation quest to find a treasure chest. One such investigation you will find on the northeast side of the map is “A Legacy of Madness“.
The first clue of the investigation is to find Cendoh the Shipwright in Telok Penjarah. You can find the location of Telok Penjarah in the image above. Upon reaching there interact with the shipwright to find new information.
The second clue can be found near the Khmoy Estate outpost. Visit the location marked in the image above to find the shipwreck location. There are multiple shipwrecks around the island but you need to find the one that contains additional information about the investigation. You will need a second-level crowbar tool to force open the shipwreck near the island.
The final clue is to locate Pieter buried treasure near the well. You can find this buried treasure in the Khmoy Estate outpost. Visit the settlement in that outpost to locate a well. You will find a reddish color icon indicating the buried treasure. Dig up the treasure to find resources, silver, ship cosmetics and complete the investigation.