Invasion of the Body Snatchers @ Grant Park

As part of the city's Outdoor Film Festival, the classic 1956 sci-fi film will be screened at Grant Park's Butler Field, at Lake Shore Drive and Monroe. Approximate starting time: 8:28 PM. Admission is free. More information: (312) 744-3370.

Author Jennifer Stevenson @ Women and Children First

Women and Children First, the independent bookstore in the Andersonville neighborhood, hosts an appearance by local author Jennifer Stevenson, to promote her new book Trash Sex Magic. Stevenson will be introduced by another local author, Audrey Niffenegger, author of The Time-Traveller's Wife. The fun happens at 7:30. Women and Children First: 5233 N. Clark. (773) 769-9299.

The Power-Ups @ Double Door

Members of the formerly-local video game tribute band The Power-Ups reunite for a summer tour of "high-energy, rocked-out" arrangements of theme music from 80s video and arcade games. Their second tour stop brings them back to Chicago, where it all began, this time at the Double Door. The band's playlist includes theme songs from Legend of Zelda, Castlevania, Super Mario Bros., and many, many more. Doors 8, show starts at 9. Tickets are $8, general admission.