Help ExplorationWorks Science Center bring STEM education to Helena and the surrounding communities. Support us by attending the best Adult Halloween Costume Party in Helena! Nightmare Affair is our largest annual fundraiser and we sure know how to raise the roof. Hosted at the Great Northern Hotel with music by Ten Years Gone and entertainment by Image Dancing, this year's Nightmare Affair is spooktacular fun for adults. Come dressed to kill because Helena is infested with ZOMBIES this Halloween!