The film tracks Kevin McKay's chaotic life in Paradise alongside his ailing mother Sherry and sick son Shaun before a faulty PG&E transmission line triggers the Camp Fire. At the depot, dispatcher Ruby reveals children remain stranded at Ponderosa Elementary. Kevin volunteers Bus No. 7, picking up teacher Mary Ludwig and 22 students just before access roads are cut off.
The journey spirals into a survival crisis as Route 191 and the Skyway become impassable grids of burning cars. Blinding smoke plunges the cabin into complete darkness, leading children to vomit and faint from noxious gas. Mary improvises face filters using a single water bottle and torn clothing; when she temporarily succumbs to despair, Kevin forcefully restores her resolve. Facing total entrapment with melting bus tires, Kevin speeds directly through an active wall of flame on a mountain route.
Bus No. 7 successfully breaks through the smoke line into Chico, where first responders rescue the surviving passengers. Kevin reunites with his son Shaun and mother Sherry, who had evacuated earlier. The final text details the Camp Fire's toll of 85 lives and PG&E's guilty plea to 84 counts of involuntary manslaughter.