Where’s Matt? Though Matt Damon spent a day in Evanston filming an upcoming action-thriller, he was all but invisible amid security and a crowd of 700 cast and crew.

Despite a fascination with the action playing out in its own front yard, Evanston minded its manners, followed the rules – and missed Matt Damon.

Director Steven Soderbergh, with a 100-member crew and 600 background actors, came to town on Dec. 10 to film a scene for the upcoming movie “Contagion.” Even at a distance from the vacant lot where Kendall College once stood, the crowd of extras, the huge crane, the fork lift and military trucks, the police and emergency vehicles marked “FEMA” and “Minnesota State Police” were hard to miss.

But almost everybody missed Matt Damon.

Lines of security sealed off the site. First came the cops, affable Evanston officers patrolling a block from the site. The cameras, they said, see everything, including bystanders. The few who came closer – a couple of dog-walking neighbors, a pair of curious reporters – met staff with smiles, official badges and reminders the all-seeing cameras might point their way at any moment.

From that distance there was no singling a star out from the crowd.

The City of Evanston had been in the loop for some time. “Several months ago,” after location scouts identified “several areas” that met their requirements, movie staff approached the City about using the property at the corner of Lincoln Street and Orrington Avenue, said Doug Gaynor, director of Parks, Recreation and Community Services.

“Contagion,” set in Minnesota, is scheduled for release on Oct. 21, 2011. The action-thriller follows the victims of a deadly disease and the international team of doctors brought to the United States by the Centers for Disease Control to cope with its spread.

The cast is as shiny as the plot is dark. The movie features Gwyneth Paltrow, Laurence Fishburne, Marianne Cotillard, Jude Law and Kate Winslet. And Matt Damon.

Auditions calling for “adult men and women (18-plus) of all shapes, sizes, types and ethnicities to be background performers” were held Sept. 25 and Nov. 16, 17 and 20. Filming began in Glenview earlier this fall.

The Evanston shoot was originally scheduled for Monday, Dec. 13, but was pushed up to Dec. 10. Three days in advance of that date, film production crews began preparing the site, transforming the empty lot into a baseball field. In the story, hundreds of residents gather there, clamoring for emergency supplies of water and food dropped from National Guard helicopters whose stand-in was the crane.

The movie required “a lot of prep work” by the City, said Mr. Gaynor, who coordinated the efforts of several departments. Those departments submitted their costs, he said, and the movie folks “pay for the whole thing.”

The City had to be sure the heavy crane would not disturb underground utilities. Traffic safety personnel had to map out detours around the restricted area, which extended several blocks beyond the filming site. City staff and production crews had to notify nearby residents of the parking restrictions and street closures 48 hours in advance, as required by City ordinance.

Asked at day’s end whether the weather had met Mr. Soderbergh’s expectations, publicist Spookie Stevens said she assumed it had; “anything with sunshine” in the midst of all the cold was all she had hoped for. Yes, Matt Damon had really been there. Filming wrapped up for the holidays on Dec. 11, she said, and will resume in January and February.

Evanston’s good behavior meant missing Matt Damon, but it did win the City at least one fan. “It’s a very sweet town. We enjoyed being there,” Ms. Stevens said. If the inconvenience pained residents, Mr. Gaynor had yet to hear about it several days later. He had been checking his e-mail for complaints, he said.

Two Lincoln Street residents finished the day with stars in their eyes. Holly Zimmerman slipped through security and photographed her husband, Lee, standing beside a grinning Matt Damon.

Others, who followed the detours and so missed seeing Mr. Damon in person may make a point of not missing the movie. But they had better not blink, lest they miss his Evanston appearance again. The scene that occupied two pages of script and a whole day’s filming will likely last only a minute on screen.