The Michigan Theater’s now-annual Labor Day weekend screening of “Casablanca” on Monday is a sure sign summer is winding down.

Most everyone knows the story.

Rick (Humphrey Bogart), an ex-freedom fighter, runs a nightclub in Casablanca during World War II. Despite pressure from the local authorities, notably crafty Capt. Renault (Claude Rains), Rick’s cafe has become a haven for refugees looking to purchase illicit letters of transit so they can escape to America.

Soon Rick is approached by handsome rebel Victor Laszlo (Paul Henreid) and his wife, Ilsa (Ingrid Bergman), Rick’s true love, who deserted him when the Nazis invaded Paris. They are looking to leave Casablanca as well. The painful reunion prompts Rick to utter the booze-soaked “Of all the gin joints in all the towns in all the world, she walks into mine.”

It’s just one of the lines from the movie that have endured in our lexicon since the film was released in 1942.

As the film unfolds, Sam will offer “As Time Goes By” on the piano (often misquoted as “play it again, Sam”), Capt. Renault will be “shocked, shocked to find that gambling is going on in here” and the police will be instructed to “round up the usual suspects.”

Surprisingly, “Casablanca” was never expected to be much of a hit. Still, the public loved it, and the film has consistently ranked near the top of lists of the greatest films of all time.

If you’ve never seen it before, check it out. It might just be “the beginning of a beautiful friendship.”

Summer Classics film series presents “Casablanca” at the Michigan Theater, 603 E Liberty St., Monday, Sept. 2 at 7 p.m. Admission is $10 (free for students with valid ID). Details at www.michtheater.org or 734-668-8397. Advance tickets at ticketweb.com. 102 minutes. Rated PG.