As Marge drives on a highway to go shopping, she finds a toll booth, but she and other Springfield residents drive through an adjacent forest trail to avoid paying. A week later, Mayor Quimby enforces tire spikes and blocks off the escape route, needing money to "de-python" the town fountain. When Marge comes up to the booth, she refuses to pay and backs up, blowing out many cars' tires, which are thrown in the tire fire. The heat and smoke from it melts ice on Mount Springfield and reveals a mailman frozen for 40 years. His letters contain many revelations and one is delivered to Homer's mother, Mona Simpson. It is from her old lifeguard boyfriend, whose name begins with an M, who writes that if Mona replies to the letter, she has chosen him, and if she does not, she is choosing to stick with her husband, Abe, and that either way, he knows the baby she is carrying is his.