Here are all five ghost achievements, for your assistance, and this is the fifth ghost.
1. This ghost is at the beach, at the south-western end, by those tall black pillars.
2. After talking to him, go to the yacht. It's towards the north-east, can be seen on a map.
3. On the pier, by the boat, you'll see an elevator.
4. Go to the top, turn to the left, and go to the pink door on the left.
5. Investigate the door, and the left side of the screen will be a magnifying glass. This will give you a vampire document.
6. Return it to the ghost for the achievement.