She insists she stays in Borneo, not by force, but by love for her husband. Apparently, Mr. Macy has signed on for a year in Borneo and decides he'd better make up with Mrs. Warwick if he's to have anything pleasant to do in the rainy jungle. Ne'er do well Mr. Robinson walks in on them and begins instigating trouble. He relates how he's been there 20 years after being offered the choice of a London jail or Borneo Jungle. He says it's a pity he can't offer Macy what has just left the room, and while Macy gets lost in visions of Mrs. Warwick, Robinson suggests there are ways and means and methods.
Mr. Warwick returns and gives Mr. Macy an earful of history about the rogue Robinson, with a warning to stay away from him. When Macy makes a suggestive comment while devouring Mrs. Warwick with his eyes, she decides to offer him the time honored helpful advice of taking a cold bath.
It's clear he doesn't get the message as he goes to meet with Robinson, who describes a kind of earwig that enjoys the human ear, but once inside, can't back out, so it goes on it's merry way consuming the human brain with deadly results within 3 weeks. Macy finds the idea repugnant and wants no part of it, until Robinson tells him he could send a friend over in the night to deliver a little visitor to Mr. Warwick's head for him. Macy decides to pay him £100 for the service.
The next morning, Macy joins the breakfasting Warwicks for some tea when he suddenly gets a tickle in his ear that makes him stick his napkin in it to find blood. He runs out of the room screaming while clutching at his ear.
The doctor is intercepted leaving the house by Robinson and we learn that two weeks have passed and Macy has got his hands tied up so he won't tear his head apart. He's not looking well. Robinson shows up to say he's truly sorry for the mistake and reassures him he'll die soon.
We next see the doctor explaining to the Warwicks that the earwig traveled through the brain and came out the other ear and that Macy has survived. When Macy emerges from the room to describe his suffering, the doctor calls him out for attempting to plant the earwig on Mr. Warwick and cause him the same suffering. Mrs. Warwick chastises him for thinking she'd turn to him as a widow. He is surprised to find out that the Warwicks will not have him arrested and that they are allowing him to leave on the next boat out. Suddenly nobody can look at him and he realizes something is up. He demands to know what they are not telling him. Mrs. Warwick is excused from the room so the doctor can deliver the terrible news.
It's clear this episode was an inspiration to Khan Noonien Singh in his plot for revenge. Mrs. Warwick seems to hold her own pretty well against the deplorable Mr. Macy. She may have done him more damage than the earwig. It was rather delightful the way Mr. Robinson came over to pay his respects and say he was sorry for the mix up. It is interesting that we never actually get to see the earwig, there's very little blood, and the horror is conveyed by the terrible notion of an earwig masticating the brain along with the expressions on Steven Macy's face. Now that's classic horror.