curtain raiser
n.— «The petition was given to the media in plenty of time for reporters to write what we in the business like to call “curtain raisers,” in advance of a big news conference that was held on Tuesday. Let it never be said that environmentalists don’t know how to generate good publicity.» —“This Climate Is Surely Full of Hot Air” by Joe Nocera New York Times Sept. 22, 2007. (source: Double-Tongued Dictionary)