After Eddie Brock's (Hardy) return to journalism following the events of the first film, "Venom" (2018), he remains bonded with Venom (also Hardy) and the pair prowl San Francisco in search of criminals to kill. Brock is soon contacted by Det. Patrick Mulligan (Graham) to speak to serial killer Cletus Kasady (Harrelson) and find the location of his victim's bodies before being executed for his crimes. After locating the bodies, Brock is invited to attend Kasady's execution. But when Venom is provoked into attacking Kasady and Kasady bites Brock's hand, the criminal ingests part of the symbiote, which blocks the execution. The new, red symbiote presents itself as Carnage, and the pair begin wreaking havoc on San Francisco.
On the eve of her departure to film school, aspiring filmmaker Katie Mitchell (Jacobson) gets in an argument with her technology-averse father, Rick (McBride), which leads to the accidental breaking of Katie's laptop. Fearing the altercation will lead to a breakdown in their relationship, Rick enlists Katie's mom (Rudolph), her brother (Rianda) and the family dog (Doug the Pug) to drive Katie across the country to school. However, while at a roadside stop in Kansas, the Mitchell family is attacked by alien robots on a mission. With the fate of human life on earth in their hands, the reluctant Mitchell family sets out to save the world.
Touring, card-counting gambler William Tell (Isaac) uses gambling as a way to numb the memories of his time as a U.S. Army torturer in Abu Ghraib. But after a chance encounter with Cirk Baufort (Sheridan), the son of another soldier from Abu Ghraib, in Atlantic City, a series of events is set in motion that leads Tell to relive the horrors of his past and choose his fate once again.