While on the subway on a school field trip, Milo’s car gets thrown off course and he, Zack and Melissa discover an underground city of subterranean creatures.

Zack, Melissa, and Milo attend an opera performance with Amanda, but Milo accidentally ends up backstage and attempts to prevent any havoc from occurring.

Milo and his friends visit a dude ranch. While horse back riding, they meet a girl named Jackie who joins their posse, and Zack is smitten with love. But, Jackie leads them into more danger than usual. Meanwhile, Sara is going crazy because the ranch reminds her of scenes from The Doctor Zone Files, and invites other fans to join in the geek fest.

Amanda is concerned that Milo will ruin everything at her carefully orchestrated school dance.

Milo, Melissa, Zack, and Mort's band enters the battle of the bands, where Zack discovers his old boy band is competing.

Milo, Zack and Melissa go to school after sunset to retrieve Melissa's math book. Unfortunately, she leaves the spare key inside the locked classroom, so the three go on a "quest" in search of the mysterious janitor, otherwise known as the "key-keeper".

Milo and Melissa finally tell Zack the story of the infamous Llama Incident.

Milo runs a race as Cavendish and Dakota gets stuck in the Old West.

With Milo away skiing, Sara finally feels safe enough to go on a date.

Zack doesn’t think anything about Halloween can scare him anymore, but he didn’t account for Murphy’s Law.

Milo surprises his parents by inviting the extended Murphy family to town for Christmas, multiplying the effects of Murphy’s Law.