With the breaking of Poseidon's Trident, every curse of the sea has been broken. As a result, things such as Will's inability to stand on the land and Salazar's ghostliness are broken... as well as a certain lost city resurfacing.
Once again captured by the British army, Jack awaits execution, but is rescued by a few old friends- Will Turner, Elizabeth Turner, and Mr. Gibbs. They ask him to help find the lost city before the Brits do.
