The narrator is a young man named Yarg who got unwillingly roped into the Singaporean pirate business. One younger man volunteers himself to explain the business because this kid and Yarg are the only crew members who know about magecraft. Yarg knows the basics and his family magecraft, but did have the opportunity to learn for real because he was second or third child, which shows in how not knowledgeable he is his narration.
The pirate explains that the Singaporean piracy business is doing sorta bad because of some Western dude who showed recently. His identity is completely unknown, and he goes only by the name "Consultant". Consultant's MO is somehow locating sunken ships (obviously with magecraft), rallying local fishermen into salvaging the ships, then making riches by selling the retrieved goods. Doing on an area this high on piracy guarantees a lot of sunken ships to be found, but it hinders the pirate business because they can't work when there're big salvage operations all over their turfs. Recently, Consultant made a dumb move and located a ship in a place with no reasonable explanation for why he'd search there. This implausible discovery deemed him as a threat to the concealment of Mystery, so Waver was sent to get him. The boy warns Yarg to be careful around Brits because they could be the Clock Tower.
In the talk about the Consultant, the kid explains about the Clock Tower with that comparison to Guan we already seen in the spoilers. He doesn't explain what thought magecraft is, but comments that the only things Western magecraft and thought magecraft have in common are the basics and the use of magical circuits.
The explanation is interrupted by Waver's magecraft failure exploding the motorboat he used to sneak into the area. With his attempt at stealth literally blown up, Waver proceeds to immediately accuse the pirate guy. The pirate attempts to attack Waver but gets backstabbed by Yarg, who reveals himself to be Gray disguised with a Mystic Code made by Flat. Waver comments that things went well this time, but for the next time, Gray needs to come with a better fake than just "Gray backwards". The prologue ends with Waver asking the pirate guy where the Consultant is.