Chapter 1: The Curious Case of the Calm Delilah

Wind on Water finds the logbook of Captain Julius Mitchell in the bag of a Kua-Toa outside of Saltmarsh. After reading it, the monster squad leaves Saltmarsh on the Persistent Imperial, led by Captain Hiroshi Takumi. They have been hired by Anders Solmor to find the wreck of the Calm Delilah, a ship that left Saltmarsh under Captain Mitchell's command over a year ago and has not been seen since. They are offered a reward if they return an Emerald Idol that was recorded as being in the hold of the Delilah, but can regardless keep anything else they find.
Along the way, they are attacked by Captain Callous, the Tiefling captain of the Red Fin, who claims to be a descendant of Asmodeus himself. They find the wreckage of a strange metallic ship which they learn to be an Illithid Spelljammer called a Nautiloid. They find no survivors.
They are attacked by a powerful ghost at sea, that they later learn to be Lavina Wisp - the mutineer first mate of the Calm Delilah. The Persistent Imperial is sunk and the surviving crew are marooned on an Island called Spiteful Shores. Over the course of the next several days, they explore Spiteful Shores, learning about the events that led to the destruction of the Calm Delilah, and gathering items and knowledge necessary to defeat Lavina Wisp before the island they are marooned on sinks beneath the waves.
They manage to find the shipwrecked remains of the Calm Delilah, defeat Lavina Wisp, and escape the island on its magically reconstituted hull as the island sinks behind them, never to surface again. They do not find the Emerald Idol, but they leave with their lives, and those of two of the Persistent Imperial's officers, as well as several magical and otherwise valuable items and a ship of their own.
The party leaves this chapter at Level 4.

Parent Plot

Act 1: Those Who Have Lost Their Way