When Marge and the kids take a seaside vacation, Homer is unwittingly tempted by a British femme fatale named Lily Marleen.
When Lily, a beautiful Englishwoman was exiled for being too exciting for her countrymen, had decided to begin a new life in Springfield. At Moe's Tavern, she enthralls the barflies, but decides that the only man she wants is Homer, who is feeling down because Marge took the kids on a vacation without him under her aunt's condition. However, Homer, missing his family, is largely indifferent to Lily, which only makes her want him more.
Meanwhile, Bart gets Lyme disease after absent-mindedly running into a forest filled with ticks and Marge, already growing tired of the vacation, takes Maggie to the dock where a crazy mob of tourists almost runs them over.
Elsewhere, Mr. Burns is spying on Lily and decides that he must have her. He commands Homer to lure Lily into meeting him on his boat, to which Homer agrees. However, when Lily runs away from the date, Homer begins to feel bad and consoles her. When Homer drives her home, they kiss, much to Homer's dismay.
Later, Marge comes home early because of the failure of her vacation and Homer gets a call from an unknown phone number, which turns out to be Lily. Homer decides that he only wants to be with Marge. Lily decides that there is nothing left for her in Springfield and she returns to England.
Back in England, Lily turns down the advances of the pubgoers until she meets a British Homer lookalike.