Two travelers—Corin Whitell, a human wizard, and Bruni Ironfist, a dwarven artificer—arrive in Tidehaven, a coastal town where the docks creak and a salt-worn lighthouse keeps watch over a treacherous reef. They answer Harbormaster Rook’s summons to investigate a rash of odd incidents plaguing the harbor. The merchant ship Seabreaker limps in after a squall, its deck crowded with exhausted sailors. In its hold lies a Coral Key, humming with imprisoned tide magic. The Key is tethered to the drowned navigator Lysor, whose ghost demands the Key’s safety lest the harbor drown in a ritual opened by a rising tide. Across Tidehaven, the Siren Circle—merchants of rumor and ritual—seek the Key to awaken a sea-demon and break the harbor’s warding barrier. A rival artificer, Nella Voss, intends to seize the Key for herself, forcing the pair to outpace both cult and thief. Main quest: locate the submerged entrance to Nereid’s Vault, a ruined temple beneath the harbor reef, and prevent the Siren Circle’s ritual by the time of the next equinox tide. The duo must decipher rune-puzzles, bargain with wary merfolk, and outmaneuver shipwright guild rivals who stand to gain from chaos. Side quest: unravel a smuggling scheme that docks cargo in hidden coves, which yields a drowned map to the Vault and a new ally among Tidehaven’s exiles. Climax: disrupt the ritual aboard Seabreaker, then plunge beneath the water to seal the vault’s wards, defeating the sea demon’s minions in a desperate underwater confrontation. Rewards: a water-breathing blessing that lasts hours, a bespoke clockwork companion for Bruni, and the Coral Key’s protective wards, plus renown as Tidehaven’s protectors. Setting and tone: a salt-wreathed harbor with tides, shipyard intrigue, eerie wrecks, and underwater exploration.