To the tunes of Tina Turner and Katy Perry, Democrats gathered four floors below ground, deep in the Washington D.C. Marriott Marquis to hear from a litany of Democrats and one "special guest" whose name did not appear on any formal program. 

The DNC filed a lawsuit against the Russian government, WikiLeaks and the Trump campaign, and its associates, arguing the parties conspired to influence the 2016 presidential campaign.