Arleen McInarnay worked on her sign to wave at vehicles entering the Westfields Marriott.= for the Bilderberg conference. (Mark Gail/THE WASHINGTON POST)

A dull office park near Dulles International Airport took on the sheen of a Hollywood thriller this week, when an invitation-only cadre of global leaders gathered for a secretive meeting known as the Bilderberg conference.

Henry Kissinger and Bill Gates were chauffeured in. Fairfax County police established a security perimeter around the Westfields Marriott and prohibited a Washington Post photographer from snapping pictures from a public street.

Outside the Jersey barriers, dozens of protesters and conspiracy theorists — convinced that Bilderberg is a global cabal that runs the world — waved signs and shouted into bullhorns.

“Honk if you hate the new world order!” they blared, hooting at drivers passing by. Fairfax police have made three arrests for a variety of misdemeanor offenses, including obstruction of justice and disorderly conduct, a police spokesman said.

“This is the true power structure, the shadow government,” said Shawn Flinchbaugh, 29. The machinist from York County, Pa., stood outside the conference center, clutching a handmade sign that read, “Bilderberg Scum.” “They say they don’t exist, but they do.”

According to its Web site, the Bilderberg meeting was organized by leaders from Western Europe and North America in the early days of the Cold War, and it is named for the Dutch hotel where the first conclave was held in 1954. The current chairman of its steering committee is a French count. Participants include the neoconservative scholar Richard Perle, billionaire Peter Thiel, and financiers such as Roger Altman and Kenneth M. Jacobs, chairman and chief executive of Lazard.

About 120 people participate in “nearly three days of informal, off-the-record discussion about topics of current concern” in economics and foreign affairs, with the crisis in Syria, the euro zone and the U.S. presidential election probably taking center stage this time.

Attendees are encouraged not to discuss the proceedings, which fuels the secrecy concerns. Many adopt a “Fight Club” approach to answering questions afterward. In other words, the first rule is, you do not talk about Bilderberg.

Over the years, conspiracy buffs have embraced notions such as the group is behind the creation of the euro and meets to select the winners and losers in the U.S. presidential election — or at least endorse the candidate’s vice presidential pick. A speech by then-Sen. John Edwards (D-N.C.) during Bilderberg in 2004 helped cement his vice presidential bid.

Vin Weber, a Washington lobbyist and former Minnesota congressman who has been a presenter at Bilderberg twice, laughs at such talk. He recalled a vigorous disagreement over presidential politics at a Bilderberg meeting, with Barack Obama supporter James A. Johnson advocating for his guy and former Bill Clinton adviser Vernon Jordan speaking up for Hillary Clinton.

“Everybody talks about this great conspiracy, but it’s really not. It’s fun to be able to talk about it,” said Weber, who is a Romney adviser.

So as the motorcades come and go, are they talking of Marco Rubio?

“Yesterday I saw three billionaires. These are the kingmakers. Whoever we see here is likely to be the vice presidential candidate,” said Mike Peachman, 24, a linguist from New York. He was keeping an eye out for Indiana Gov. Mitch Daniels (R), a scheduled presenter sometimes mentioned as a Romney vice presidential pick. (Also on the invitation list was Donald E. Graham, chairman of the board and chief executive of The Washington Post Co.)

Every once in a while a van with tinted windows would drive through the gate, and the crowd of protesters would chant, “Scum, scum, scum!” as it sailed by. But then the sky darkened, and severe thunderstorms came sweeping through, ruining everything.

The timing couldn’t have been more perfect if the Lords of Bilderberg had arranged it themselves.