The year is 2022, and after an unlikely event, only one man is left on earth: Phil Miller, who used to be just an average guy who loved his family and hated his job at the bank. Now, in his RV, Phil searches the country for other survivors. He has traveled to every city, every town and every outpost in the United States, Mexico and Canada, and has found no one, which leads him to the painful realization that he is almost certainly the last living being on the face of the earth.
Pamela finds her place within the group as they all set sail for Mexico, avoiding the apocalyptic nuclear fallout in the United States. Their course derails a bit when they realize that none of them knows how to actually navigate a yacht.
Tandy devises an escape plan to get away from Pamela and back to Carol and the others. Meanwhile, the rest of the gang encounters a castaway, Glenn, who has been stranded on an island for years.
Pamela tries desperately to redeem herself with everyone, as the gang finally reaches Mexico. Meanwhile, Todd is disappointed that Zihuatanejo is not the paradise of which he'd dreamed.
Carol panics when Todd and Melissa leave for their honeymoon and Erica and Gail decide to live on their own for a while. She and Tandy devise the ultimate plan to convince everyone it's safer to stick together.
The gang settles into an old mansion previously owned by an infamous cartel leader. While Carol forces Tandy to put down his new toys so they can baby-proof the giant estate, Melissa worries about Todd's physical health and Gail and Erica can't figure out why Dawn won't stop crying.
Carol's pregnancy takes an unexpected turn, and while Tandy feels ready to face the challenge head on, Gail is concerned and wants to intervene. Meanwhile, Melissa discourages Todd's baby fever.
Tandy goes to great lengths to convince everyone he's a feminist. Meanwhile, Carol gets jealous of the time that Gail spends with Erica and Dawn, and Todd tries to be a father figure to Jasper.
Todd asks Tandy for parenting advice when he notices that Jasper is acting more reckless than usual. Meanwhile, Carol and Erica realize that Jasper may be the only potential suitor for their babies and begin vying for his attention.