In 1981, Camp Firewood, a summer camp located near Waterville, Maine, is preparing for its last day of camp. Counselors have one last chance to have a romantic encounter with another person at Camp Firewood. All the while, Ben and Susie, two overzealous drama instructors, attempt to produce and choreograph the greatest talent show Camp Firewood has ever seen.
Beth, the camp director, struggles to keep her counselors in order—and her campers alive—while falling in love with Henry, an astrophysics associate professor at Colby College. Henry has to devise a plan to save the camp from a piece of NASA's Skylab, which is falling to Earth.
Shy Coop has a crush on Katie, his fellow counselor, but has to pry her away from her rebellious, obnoxious, and obviously unfaithful boyfriend, Andy. Only Gene, the shell-shocked Vietnam war veteran and camp chef, can help Coop win Katie—with some help from a talking can of mixed vegetables.
Gary, Gene's unfortunately chosen apprentice, and J.J. attempt to figure out why their friend McKinley has never been with a woman. They are surprised to find that McKinley is in love with Ben, whom he marries in a ceremony at the lake. Victor attempts to lose his virginity with the resident loose-girl Abby, but a series of mishaps get in his way.
Janeane Garofalo as Beth
David Hyde Pierce as Professor Henry Newman
Molly Shannon as Gail von Kleinenstein
Paul Rudd as Andy
Christopher Meloni as Gene
Michael Showalter as Gerald "Coop" Cooperberg/Alan Shemper
Marguerite Moreau as Katie Finnerty
Ken Marino as Victor Pulak
Michael Ian Black as McKinley
Zak Orth as J.J.
A. D. Miles as Gary
Amy Poehler as Susie
Bradley Cooper as Ben
Marisa Ryan as Abby Bernstein
Kevin Sussman as Steve
Elizabeth Banks as Lindsay
Joe Lo Truglio as Neil
Judah Friedlander as Ron von Kleinenstein
Gideon Jacobs as Aaron
H. Jon Benjamin as Can of Mixed Vegetables