Marge's protest against a toll booth causes an accident at the Springfield Tire Yard (which has been perpetually on fire since the 1980s), melting a frozen section of a mountain and revealing the corpse of a mailman who has a letter from Homer's mom, who had an affair with a handsome lifeguard who may be Homer's biological father.

!! Tropes:

* MamasBabyPapasMaybe: Homer isn't sure if his real father is Abe Simpson or Mason Fairbanks.
* MyLifeFlashedBeforeMyEyes: Homer experiences it near the end and finally remembers [[spoiler:the good moments he spent with Abe Simpson]].
* TheScrooge: Everyone who'd rather take "The Ol' Cheapstake's Trail" than pay the toll.