Although Edgin, Simon, Holga, and Doric had spent a long time in panic and disarray that night over Annie's disappearance, their search had ultimately come up empty. Once Simon confirmed he couldn't attune to the Helm of Disjunction, they came up with an alternative "Plan B."
The general outline of this so-called "Plan B" was:
First, find something—say, a treasure or some other valuable item, like a famous painting?
Then, use the teleportation staff ahead of time to attach one side of a portal to the painting. Next, disguise the "portal" painting as a treasure, mix it in with the other valuables, and somehow get it into Neverwinter's vault.
That way, they could slip into the vault without having to break through that troublesome Mordenkainen's seal and make off with all of Forge's treasures!
Originally, though, the plan would have been very, very difficult to pull off.
Fortunately, since the "Suns' Tournament" was being held, many wealthy people from Baldur's Gate and Waterdeep—the lords and nobles who were competing or placing bets—would bring their treasures to Neverwinter and store them in the city's vault, where they would be kept temporarily by the tournament's organizers: Neverwinter.
And that was exactly the opening Edgin and the others needed!
So, after realizing Annie really had vanished and had no idea where she'd gone off to play, the four of them knew they couldn't afford to wait. They came up with what they thought was a highly workable plan that very night and prepared to put it into action.
Of course, if Simon had suddenly managed to attune to the Helm of Disjunction before then, they might still have opted for the much simpler "Plan A."
In any case!
Annie had no idea whether Edgin and the others' plan had succeeded or how far