Beloved characters from The Big Bang Theory face an apocalyptic dilemma in a spin-off comedy series, which unfolds in weekly instalments. Comic bookstore owner Stuart Bloom (Kevin Sussman) accidentally breaks a device built by Sheldon and Leonard. His actions initiate a multiverse Armageddon and Stuart faces a race against time to restore reality. His girlfriend Denise (Lauren Lapkus), geologist friend Bert Kibbler (Brian Posehn) and quantum physicist Barry Kripke (John Ross Bowie) join Stuart on this madcap endeavour. As Stuart and co repair temporal damage, they encounter alternate-universe versions of characters from the main series