Sometime after Scarlett spares Mercutio as part of the Secret Errands quest, but before entering the Warehouse as part of the Bad News quest, she should approach Tusker aboard the Pirate Ship in the Harbor and ask him for a job. (Scarlett may need to resolve her issues with Tusker from his previous betrayal in The Pathway to the Claw quest earlier. Whether she forgives him or attacks him doesn't matter; he's apparently flexible and will still offer her a job.)
This quest and the Sea Patrol quest are mutually exclusive. Which she is eligible for depends on whether she kills Mercutio or not during the Secret Errands quest. And it is only available after she spares Mercutio. (If Scarlett is not eligible for this quest because she killed Mercutio, she will be eligible for the Sea Patrol quest instead.)
Furthermore, the quest is available for a limited time: until she completes the Bad News quest. If Scarlett approaches Tusker before the Secret Errands quest, he will not offer her a job. If she approaches him after completing the Bad News quest, she will have to ask him for passage to Africa instead, as part of the The Hunted Becomes The Hunter quest. After Scarlett has been to Africa, the Pirate Ship will no longer be at the Harbor.
- Secret Errands - (prerequisite) - Scarlett must have completed this quest by sparing Mercutio and stealing the key she needed instead.
- Scarlett must perform this quest before completing the Bad News quest by entering the Warehouse the second time (with her guild helpers).
This quest is pretty direct: As soon as Scarlett accepts the job offer from Tusker, the pirate ship will set sail and Scarlett will find herself in the Captain's Cabin with Tusker, who will tell her they have caught a Merchant Ship along side.
Scarlett must kill all the Sailors (whose Health Bars label them Rogue Masters). They are on the deck of and inside the hold and cabins of their ship. After killing the Venetian Captain (whose Health Bar labels him a Necromancer, she should search his body for a key. It opens the chest in the Captain's cabin. (There is a chest in the cargo hold with some loot if Scarlett wants.)
There are four parcels Tusker wants:
- On the mid-deck, beneath main mast.
- On the aft deck.
- In the chest in Captain's forward cabin. (Requires key looted from body of Captain.)
- In the main cargo hold.
- Sea Patrol - (mutually exclusive) - Scarlett can sign on board the Charming Princess and hunt Pirates, instead.
- Secret Errands - (prerequisite) - Scarlett must have completed this quest by killing Mercutio.
- Bad News - Scarlett must perform this quest before completing the Bad News quest.
- The Hunted Becomes The Hunter - Scarlett will need to travel on this Pirate Ship again after she completes the Bad News quest.