Connecting Statement:

While Paul was in the prison at the fortress, the disbelieving religious Jews vow to kill him.

formed a conspiracy

"organized a group with a shared purpose" here, to kill Paul.

The noun "curse" can be translated as a verb. It can also be made explicit what would cause them to be cursed. AT: "asked God to curse them if they did not do what they promised" (See: rc://en/ta/man/translate/figs-abstractnouns and rc://en/ta/man/translate/figs-explicit)

"who made this plan" or "who planned to kill Paul"