A chemical engineer, who recently moved to town, struggles to find a way to kill a deadly new variant of Cryptosporidium that has infiltrated the town's water supply, causing people who drink it to die of thirst.

Curtis Pike and his family are selected to test a new home device: a digital assistant called AIA. AIA observes the family's behaviors and begins to anticipate their needs. And she can – and will – make sure nothing – and no one – gets in her family's way.

Late one night, Billy and Kade Ruckman see their neighbor, Michael Chambers, murder a woman, but Chambers has a story all set to convince their mother Vicky, that it was just a rehearsal scene from an opera. The only ones who can help them find the body in Chambers' house before he moves and gets rid of all evidence, are their friends, Jimmy, Eddie, and J.J., who are determined to find the body before Chambers finds them.

Mollie and James are together and raising a family, which now consists of an older Mikey and his baby sister, Julie. Tension between the siblings arises, and as well with Mollie and James when Mollie's brother Stuart moves in. Mikey is also learning how to use the toilet for the first time.