Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Initial Situation
Gregor wakes up one morning and finds himself turned into a bug.
It seems odd to begin a story with what should be the ending. After all, all kinds of questions are probably swimming in your head. Like, how did he become a bug? What is this story? Is it a fantasy? A myth? How could it possibly be "realistic"?
But that's what makes the opening of Kafka's Metamorphosis such a head trip. Because these are the questions that Gregor—and, arguably, the story—ignores. Both Gregor and the story treat Gregor's metamorphosis as though it were just an ordinary day—an ordinary bad day, sure, but nothing extraordinarily bad.
Conflict
Gregor is met with horror and disgust when he reveals his new form to his family and his supervisor.
Not surprisingly, Gregor's transformation causes some friction with his family and his employer. It's hard to be an effective salesman if you're a bug. Since Gregor can no longer support the family, the family can no longer remain as they are—an invalid father, an asthmatic mother, a flighty teenage sister. They must all seek work and find ways to cut household costs.
Complication
Both Gregor and his family attempt to accommodate Gregor's new condition.
Gregor's family has no idea how to treat this thing that he's become. Swat him with a rolled-up newspaper as if he were a common household pest? His father seems to feel that way when he chases Gregor back into his room. Or care for him as if he had some unfortunate and incurable disease, as Grete does? Torn between her revulsion at Gregor the pest and her sentimental attachment to Gregor the son, Gregor's mother spends most of the time waxing sentimental about Gregor or wheezing through another panic-induced asthmatic attack.
Climax
Moved by his sister's violin-playing, Gregor leaves his room in an effort to approach her. He exposes himself to the family's boarders, however, and chaos ensues.
Up to this point, the family has grown accustomed to life after Gregor's transformation. In addition to his twice-a-day feedings, the family leaves the door ajar every evening so that Gregor can witness the family's nightly routine. But on the night that Grete plays the violin, Gregor is so overwhelmed by emotion that he breaks free from his room in an attempt to contact her. Instead of being moved by Gregor's gesture, the family is appalled. It doesn't help that Gregor frightens away the boarders (an important source of income).
Suspense
After some discussion, the family agrees that they must get rid of Gregor.
While Gregor has escaped his room twice before, his third escape is the last straw for his family. They read his escape as his unwillingness to remain in his room, out of sight and out of mind. They believe he wants to take over the entire apartment and ruin their lives.
His behavior is seen as inconsiderate and decidedly inhuman—certain evidence that he is no longer Gregor, the loving human son who used to support them, but a disgusting bug through and through. Gregor, who happens to be lying in the middle of the floor as the family discussion swirls around him, silently agrees and lurches back into his room.
Denouement
Gregor dies.
Poor Gregor. On top of being a loathsome insect, he has to witness his family's horror, poverty, and humiliation. Gregor's pathetic death ends the trials and tribulations that were set off by his metamorphosis.
Conclusion
Relieved by Gregor's death, the family takes the day off and goes out for a trip to the country. Mr. and Mrs. Samsa notice that Grete has become a marriageable young woman.
The story's ending confirms Gregor's bleak realization that his family is better off without him. No longer do they shuffle under the weight of all their troubles. Grete's stretch at the end of their train ride out to the country represents the entire family's feeling that a huge burden has been lifted off their shoulders.