Finding and Defeating La Plume

With the Sainte-Amelie plunder complete, set sail towards the Southwest Passage. Use your spyglass to locate the high-level ship known as La Plume. Engage in battle with La Plume to obtain the final clue required to Skull and Bones Items complete the investigation. This battle will be intense, so ensure your ship is well-prepared and fully stocked with ammunition and repair kits.
Returning to Sainte-Anne and Completing the Investigation

After defeating La Plume, you can either fast-travel back to Sainte-Anne using an outpost or sail back manually. Once you return to Sainte-Anne, head to the Warehouse and speak with Anja Rakotomang to conclude the "Turning the Page" investigation.

Completing this investigation will solve the mystery surrounding 'Kit the Tiger' and reward you with valuable loot. Make sure to cheap Skull and Bones Items collect your rewards and prepare for future investigations with the insights you've gained from this challenging quest.