The Great Brain Robbery

Beginning
''Item(s) required: 4 planks, ~20 nails, a hammer, fishbowl helmet, diving apparatus, holy symbol. Good food and some armour to defend from aggressive level 57 Zombie pirates''

Optional item(s): Ectophial, charged glory (teleport to Edgeville), 3 watermelon seeds, a rake, seed dibber, some Super-compost and a spade (A Tool Leprechaun is located nearby)—the latter five items are necessary only if you wish to complete a hard task for the Morytania Diary.

NOTE: Leave your follower in the bank, or you will not be able to go diving.

Use a Charter ship to Port Phasmatys; talk to Bill Teach on his boat in Port Phasmatys at the east end of the dock near the Green Ghost Inn. Agree to sail with Bill to Mos Le'Harmless. You may opt to use the Mos le'harmless teleport scroll, or to use the Trouble Brewing minigame teleport. Near the dock, you will notice a rather sickly-looking monk named Brother Tranquility. Talk to him to begin the quest—select the option regarding undead pirates. He will explain how some of his fellow monks are in trouble and asks for help. Accept the offer to be teleported to Harmony Island.

Gathering info
Make sure you have the supplies listed earlier and head outside the windmill. Zombie pirates (level 57) are aggressive and will attack. A short way to the north will be a Saradomin statue that can be pulled. Pull the statue. Go down the hole and into a tunnel. It is full of water, so equip the diving gear to submerge beneath the water. Note that you cannot enter the water if you are carrying a follower such as a pet cat. Run past the zombie pirates and repair the stairs at the far end of the tunnel (you can be attacked while repairing the stairs and it takes a while). Climb up them, climb up the ladder in the next room; then, look through the peephole to spy on the enemy.

Tip: If you plan on completing a hard task for the Morytania Diary, plant and harvest some watermelon (requires 47 Farming) in the nearby allotment patch.

The Prayer Book
Report back to Brother Tranquility. He will suggest getting a book that can be used to pray away poison. Travel to the Monastery near Edgeville to find the prayer book in a bookshelf towards the south-west corner of the building on the ground floor. Read the book, which provides instructions on how to use it. Equip a holy symbol and return to Harmony Island. The zombies have begun to gas the windmill, so right-click the book and select "recite-prayer." After this, make sure to talk to Brother Tranquility.

The Doctor
Item(s) required: Ring of charos

Optional item(s): Ectophial, armour, food, weapon and/or Wolfbane dagger. Now that the monks are no longer in danger of being poisoned, they would like to get their brains back in their bodies where they belong. Travel to Dr. Fenkenstrain in his castle and climb up to the jail where Lord Rologarth (Fenkenstrain's monster) was first held. After a bit of negotiation, he agrees that a new home free of the threat of being eaten sounds better than where he is. However, he does not want to risk being eaten while traveling. He is allergic to teleportation, so another way needs to be found.

Head to Canifis and talk to Rufus, the owner of the meat store north of the bank. Make sure to be wearing the ring of charos while talking to him. Rufus will give you some crate parts and a wolf whistle. You need to build ten decoy cats to fill the crate since Rufus assumes the crate will be transporting cats.

''Tip: Since you are right next to a bank, deposit the whistle and crate parts and take out Mos Le'Harmless teleport (treasure trail), 10 wooden planks, 10 pieces of fur, and a hammer — home teleport runes or tab and an ectophial are advised for easy traveling. Also, if you still need fur, you can kill Canifis villagers—they'll transform into level 88 werewolves if you don't use Wolfbane, so be careful. You can also obtain fur by thieving from stalls in Ardougne (or trading the fur trader there) or by purchasing fur in Varrock square for 20 coins apiece. Ultimate ironmen may find a table in the south-east tower of Fenkenstrain's castle, on the first floor helpful.'' Travel to a Player-owned house that has a crafting table. Craft the materials into 10 wooden cats. Grab your ring of charos, the 10 wooden cats, 4 planks, a hammer, ~50 nails, the crate parts, and the wolf whistle before traveling back to Fenkenstrain's castle. When you get to the room where the doctor is hiding, you'll see a hotspot to build the crate. Do so, and then, use the extra planks of wood to build a false bottom by clicking on the crate again and selecting "add-bottom." Fill it with the fake cats and then use the wolf whistle Rufus gave you to call him. Fenkenstrain will automatically get in the crate. Once past inspection, Rufus will give you a shipping order. Use this on the crate, and it will be teleported to the island.

Making the transplants
Now that the doctor is on the island, travel back to Mos Le'Harmless. Use the island bank to grab a hammer, diving gear, armour, and a weapon before teleporting to Harmony Island. Dr. Fenkenstrain is in the basement and needs some equipment to perform the surgery. He will give you a list of items to collect:
 * Brain tongs
 * Cranial clamp
 * 3 bell jars
 * 30 skull staples
 * A hammer

Luckily, the bad guys already have what you need since they performed the surgery in the first place. The only problem is how to get inside the building... Put on the diving suit to avoid passing out from the gas, and head north from the windmill to the ship beached nearby. Search the locker on the ground floor to get a fuse; then, climb up a level and get a tinderbox and a keg of powder. With these in hand, go back to the front door of the monastery. Wedge the keg in the front door, add a fuse, and then, light it. The door is now open.

Once inside, kill the 4 Sorebones to obtain all the needed equipment. Walk back to the windmill, head downstairs, and give all this to Dr. Fenkenstrain to begin the gruesome surgery. A cutscene of a cute cat playing with a ball will ensue due to the surgery being too gruesome. Make sure to speak to Brother Tranquility after the operation.

The big battle
 Warning: If you die, you will not be able to retrieve your items. Return to the bank on Mos Le'Harmless and grab all the armour, food, and potions you will need for the fight.  Warning:  You still need to wear your diving suit.

When you enter the monastery, only Mi-Gor will be there, giving you the option to confront him. When you do, he will summon his monstrosity, a giant mess of machinery named Barrelchest, to attack you.

Prayer (and also defence) drains faster than usual during the fight, and Barrelchest will turn your prayers off, but just keep turning it back on (note: Repeatedly turning it on can be a huge time waste and result in death if he gets lucky with the timing of his hits, plan to do this without prayer to avoid that). Bringing several prayer potions and at least ten good food is highly recommended. Barrelchest is a fairly blunt instrument; he will not use anything but Melee attacks, which are fairly inaccurate; however, when he does hit, they are almost always 20's. It is possible to catch him on the side of a pew and attack him from a distance without any sort of retaliation by standing behind benches for safespotting. This makes ranging or maging an incredibly effective way to take out Barrelchest. However, do not hide behind a pew when attempting to do this. Catch him on the corner of the first pew by taking a few steps back when you first start the battle, or he will strike the ground with his anchor and cause 25 damage. Alternatively... just teleport out when you encounter him and make your way back to the boss room but don't move anywhere; the spot you will be standing in serves as a safespot.

Once you have killed Barrelchest, pick up his anchor and walk back to the windmill to inform Brother Tranquility of your victory. He will thank you and give you a lamp granting 5,000 experience in the skill of your choice. Congratulations!

''Tip: If you've grown your watermelons already, don't forget to pick them in order to complete the hard task.

Tip: If you died during the boss fight, remember to pickpocket Dr. Fenkenstrain to receive another ring of charos.

Music

 * Zombiism

Tips

 * Having the Book o' piracy allows you to skip the first speech with Bill Teach in getting him to transport you to Mos Le'Harmless.
 * You don't need to fully complete the quest to receive and use the barrelchest anchor—you just need to kill Barrelchest.
 * A Kharyrll Teleport (Canifis teleport) in your house provides faster return to Fenkenstrain's house after creating the fake cats.
 * The Charter ships are a useful (if pricey) way to get to Mos Le'Harmless and Port Khazard.
 * Talk to the pirate at the docks of Mos Le'Harmless to convert the anchor to a two-handed weapon for a fee of 230,000 coins (see above, under reward).
 * Barrelchest is a large enemy, which allows for the dragon halberd special attack to be useful, although you cannot safespot with a halberd because of Barrelchest's wide attacks.
 * The "blessed lamp" is a bankable lamp, great for saving for the last 5000 experience for a 99.

Trivia

 * The title of the quest is probably a reference to a 1903 movie titled "The Great Train Robbery", though there's also a book and a song by the same name. Wikipedia has several pages describing the Great Train Robbery.
 * The music Zombiism when on Harmony Island comes from the movie The Great Train Robbery (1903 film).
 * Another Monty Python reference is hidden in the quest. When Rufus comments that the cats aren't moving, the character will comment that they're "probably pining", referring to "The Dead Parrot Sketch".
 * The Mi-Gor character and Barrelchest monster are probably references to emphysema, a fatal lung disease that leaves victims with a "barrelchest" and a scary voice.
 * This quest marks the second appearance of Elfinlocks, a fake player from the Draynor bank robbery plot, who is travelling with her clockwork cat in Canifis. She appears to have gained another blue partyhat since her last appearance.
 * When first going to Harmony Island, the player does the "Scared" emote saying that they're afraid of getting hit while transporting. This is a reference to the transportation method used in Rum Deal.
 * The crate hotspot is the only known hotspot that is made outside of your house.
 * If you are wearing the fishbowl helmet and you blow the whistle to call Rufus, you'll get the following message "You should take your diving helmet off before you try to blow the whistle."
 * If you get the Mysterious Old Man or Dr. Jekyll random events while you are underwater, they will also be wearing a fishbowl helmet.
 * When Dr Fenkenstrain tells you the list of equipment he needs, the player says mentions "Unusual Implements R Us". This is probably a reference to the American toy store "Toys R Us".
 * "Not the box" is probably a reference to the film Hook and the Boo Box