The Passage follows several groups as they experience a pole shift and are increasingly introduced to friendly aliens. These themes and the cover-up over the
approaching danger are introduced early. Martha, as a child, and her young son Billy are both shown to be contactees. The cover-up over the approaching rogue
planet that will cause the pole shift is encountered when the public tries to use observatory telescopes.
Danny, a young journalist encounters the pole shift cover-up when he tries to publish a theory held by a local East Coast professor. The story follows Danny. Discouraged at being dismissed by his editor, Mr. Maya, he goes on a camping trip to the West with his girl friend Daisy. Hitting it off with another couple, Frank and Jane, up in the Rockies, they discuss professor Isaac's theories and the congruence of prophecy, folklore, and geographic evidence.
A local rancher, Big Tom, finds his cattle restless and his wife Martha drinking beer in the middle of the day when the earth starts moaning. The pole shift hits, preceded by days of darkness, red dust, and a slowing rotation. A tent city is erected. An old timer at the ranch, Red, keeps the family on an even keel. Martha and Red feed the group possum and earthworms and Red cobbles together a windmill from a lawnmower and car parts.
Various groups migrate to a local ranch, as the roads and communications are disrupted. Danny and his friends are looking for a working phone and some gas for their car. The local Mayor, Herman, along with a couple close to the ranch folks, Len and Clara, are looking for any place not devastated. Netty, the lone survivor at a resort, is being pursued by the Groggin brothers, who are dealt with in vigilante style justice. Mark, the pilot of a downed small plane, and his lover Brian are looking for rescue. The group shares stories.
Insanity due to the stress of the changes affect little Tammy and Brian. Young Billy receives a gift from the Zetas to cure his sister. Mark takes Brian back to the plane wreck to rig an air balloon, traveling under strong west winds to New York City, viewing the devastation as they go.
The group gathering at the ranch soon encounter a rogue military unit, lead by General Flood and his acquiescing assistant Sergeant Hammond. They must leave the ranch for their own safety after Jane has been killed during a rape attempt. The traveling band lives off the land as their supplies have run out. The group find evidence of cannibalism.
The traveling group then encounter another survival group led by Ian, established on a river bluff. There Frank meets a new love in Madge, a mute cook. Red helps an old timer at the camp cobble together a wood gas generator for the antique tractor.
The rogue military unit follows, as Colonel Cage and others assigned to quell the ranch rebellion have broken orders. On the move again, the group encounter an innovative houseboat city afloat in the river, using plastic bottles as floatation devices. They arrive at a dome city under the protection of benign visitors, the Zetas. The dome city is self sufficient, growing food indoors. The city mayor, Jonah, is an obvious contactee and hybrid children live at the dome city. After a battle in which the protection of the Zetas plays a part, the residents of the dome city find they have some friendly new neighbors, not entirely human.
Danny and Netty are taken on a tour to meet alien lifeforms. Billy is the tour guide. They meet an intelligent octopus, a hominoid pair with thick plate covered skin, an intelligent jellyfish in a living ball of water, and intelligent manta rays living on a poisonous gaseous planet.