After the British leave the Galapagos, they sail to intercept the Acheron, which was spotted by the doctor when he was looking for specimens. While the doctor and Aubrey are talking, the doctor mentions how some species of insects have evolved to look like part of their environment to avoid predators. Captain Aubrey devises a plan to disguise the Surprise as a whaling vessel and ambush the Acheron. This goes almost according to plan, and they capture the Acheron, although a number of the Surprise's crew are killed or seriously wounded. The captured Acheron, now commanded by one of the Surprise's officers, sets sail for an English port. Just as the Surprise is about to head back to the Galapagos so the doctor can find a specimen of a new bird species he discovered, the captain and the doctor realize that the French captain is still alive and aboard the Acheron with the other captives. The Surprise turns around and escorts the Acheron to port, much to the dismay to the doctor.