Hogan “Hoagie” Malloy, Bob Callahan, Randy “Chilli” Cilliano, Kevin Sable and Jerry Pierce have been playing the same game of tag since they were nine years old, starting in 1983, during the month of May. Since then, the group’s main rule of the game is that the last one tagged is “it,” until next season. With Hoagie having been the last one tagged in the previous year, he first tags Bob, now the CEO of an insurance company, by getting hired on at Bob’s company as a janitor. He recruits Bob and then Chilli and Kevin for one last attempt to tag Jerry, who has never been tagged because of his strong athleticism and intelligence. Hoagie tells them that Jerry plans to retire after this year’s game because of his upcoming marriage. Rebecca Crosby, a Wall Street Journal reporter doing a piece on Bob, learns of their game and joins them, deciding to write an article on the friends. They are also accompanied by Hoagie’s wife Anna, who is not allowed to play as their rules state that girls weren’t allowed to play, and also because she is extremely competitive.
Once they arrive at their hometown of Spokane, Washington, they lure Jerry to the local country club where he will be getting married, but they are overwhelmed by Jerry’s skill. Jerry then introduces his fiancée Susan. As the others express disappointment over not being invited to the wedding despite their close relationship, Susan explains that they were not invited because she did not want to have her wedding ruined by their tagging shenanigans. They agree to not play the game at any wedding-related events in exchange for invitations to the wedding. Despite this, the group makes several attempts to tag Jerry both before and right after wedding-related events.
The group sneaks into his house at night, learning that Jerry has upped his game with various outfits and even Chloroform. Hoagie also notices a receipt for Jerry’s tuxedo, learning that he will pick it up the next morning. Before they could learn anything more, they are forced to leave when Jerry sets up a convincing ruse that he is in Hoagie’s bedroom with his old stuffed bear from childhood, but in actuality, he was in his own basement the whole time. The next morning, Hoagie, knowing where Jerry will be, disguises himself as an elderly woman and ambushes Jerry at the mall, but is defeated. Then, at a rehearsal dinner at the country club, Jerry invites Cheryl Deakins, Bob and Chilli’s high school crush, to distract the group, and the attempt to tag Jerry results in a golf car chase that eventually leaves Hoagie, Chilli, and Kevin all caught in painful traps in the woods, set by Jerry and the golf grounds crew. During the rehearsal dinner, Susan reveals to the guys that she is pregnant.
Defeated, the group try to build a new plan. After finding out Jerry attends Alcoholics Anonymous meetings, the group decide to strike his next meeting, which is on his wedding day. In preparation, they lock every exit, lay mousetraps on the ground outside to keep Jerry from jumping from windows, and dress up as members of AA. They make their move and almost tag Jerry, but once he finds himself trapped, Jerry retreats to the communion wine storage. He stays there for hours as the guys besiege the room, until Susan comes by, with the wedding just a few hours away. Susan berates Jerry and the others for risking the wedding for a childish game but suddenly appears to fall faint and have a miscarriage. Jerry comes out to help. Chilli is convinced that it is a ruse, but the situation seems authentic, and Jerry himself also tells them he is not playing around and the two leave.
The guys receive texts that the wedding is postponed due to the potential miscarriage. However, a suspicious Anna sees that the bridesmaids all made similar Instagram posts. With one of the bridesmaids having a crush on Bob, and also having a private profile, Anna creates a fake profile for Bob in order to bait the bridesmaid for the truth. Once they get access, they see a post from the bridesmaid of Susan in her dress, showing that the wedding is still on schedule. Incensed by the trick, the gang decide to crash the wedding. Upon their arrival, Susan confirms the hoax, including the pregnancy being fake. Angry at Jerry for lying, Hoagie decides to tag Jerry at the end of the ceremony after the doves are released. Hoagie charges at Jerry, but narrowly misses and ends up accidentally tackling the pastor to the ground. Hoagie then loses consciousness, which Jerry thinks is a ruse, but Anna confirms that Hoagie’s condition is serious and calls for an ambulance.
Everyone meets up at the hospital where Hoagie tells them he has liver cancer. Knowing he may not be alive for the next season, Hoagie lied about Jerry quitting because he wanted to reunite everyone for one last attempt to tag him. Jerry laments at not being as close to the rest of the group, and states that it should have been the four of them up there as his groomsmen. At his friends and wife’s urging, Jerry finally swallows his pride and allows Hoagie to tag him. With only five minutes left the group continues the game, running around the hospital as they did as children, and change their rules so Anna, Rebecca, and Susan can play as well.
Before the credits roll, multiple photographs and video clips are displayed, showing the real group of ten men that inspired the film, who continue to play to this day