New content is coming to Guild Wars 2 for a new Halloween story set to kick off in phases starting October 22nd. ArenaNet has launched a teaser site for the Shadow of the Mad King update that details the gradual unlocking of the new four-act storyline with the first opening with the launch of the new content on October 22nd. Act 2 will open on October 26th with Act 3 on October 28th and the final act on Halloween.
Visit the Shadow of the Mad King update page to learn more and get a look at the update trailer below.
Source: Guild Wars 2 Halloween