Gregor wakes up and finds that he's turned into a huge cockroach (or other vermin—the text doesn't specify exactly, though the descriptions match a cockroach's). The famous opening line: "As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect."
The text never explains why Gregor transforms, fitting with Kafka's profound interest in the random, tragic absurdity of life. The sudden transformation also shows the weakness of the mind, which can't control the physical reality of the body.
Gregor examines his body, immediately understanding that he isn't dreaming. He looks around his room, containing the cloth samples for his job as a traveling salesman, and a framed print of a lady wearing a muff. He looks out the window at the gray day and feels sad. He wants to go back to sleep, but his awkward new body prevents him from getting into a comfortable position. He tries a hundred times to roll onto his side and each time can't maintain the position.
The story may be surreal, but Kafka demonstrates early on that this isn't a magical dream, but rather, a heightened reflection of reality. Though his body has changed, Gregor's concerns remain focused on pragmatic, everyday things: finances and his responsibility to his family.
Gregor frets about his exhausting job. He notices that his belly itches, but when he touches the area with a leg he feels "a cold shiver." He ruminates on the importance of sleep, and thinks about how he'd like to criticize his boss to his face, except for the fact that he has to keep working to support his parents. In a few years he will have paid off his parents' debt. Gregor notices that he slept through his alarm and now he's missed his five a.m. train. He worries about missing work, and doesn't think he can take a sick day, since he hasn't taken one in five years.
Gregor's new body intrudes on his thoughts about his human life, already showing how body and mind are not separate, but closely linked, with the body influencing the mind. We see Gregor's selfless side and devotion to his family—he's working not just to support his family, but to make up his parents' debt. He's taken on extra responsibility, and given up his own life to the needs of his family.
Gregor's mother knocks to wake him, and Gregor thanks her in a strangely squeaky voice. Gregor's father begins to knock to ask what's wrong, and then his sister Grete asks him if he needs anything and tells him to open the door. Gregor is glad that he locked the door the previous night.
Gregor's ability to speak has been impaired by his metamorphosis—little by little he's coming to realize his new limitations. In this first scene with his family, their concern and love for him is evident. Though one might also note more cynically that their concern may depend in part on the fact that they depend on Gregor's income to support them.
Gregor expects that once he gets up he'll feel better. However, he finds it hard to control his new body, and injures himself attempting to get out of bed. He pauses and rationally decides that he simply can't stay in bed, then makes a new effort to get up.
Though Gregor's previous life was devoted to the routines of responsibility to others, now he has a new burden of responsibility—his own body makes him work and hinders him.
Gregor's boss, the Chief Clerk, arrives at the door, just as Gregor falls to the carpet. Gregor hates that his absence has been noted so quickly, and feels that he should be given a break, especially in front of his family. Grete and Gregor's father tell Gregor that the clerk has arrived. Gregor hears his mother defending him to the clerk, saying that Gregor is always dutiful and singularly focused on work.
Gregor's family demonstrates loyalty to Gregor, with the added complexity that they depend on Gregor for their livelihood. As is often the case in the story, intentions are complicated—a positive-seeming surface can mask a harsher reality, and vice versa.
Gregor refuses to open his door for the Chief Clerk, and Grete begins to cry. The clerk calls Gregor "incredibly obstinate" and explains that Gregor's job may be in jeopardy. Gregor gives a long, polite speech, attempting to defend himself, then tries unsuccessfully to open the door.
This scene vividly illustrates both Gregor's lack of understanding about himself, and, on a larger level, the failure of words and the mind to overcome physical realities.
The Chief Clerk doesn't understand Gregor's speech, and exclaims that a human couldn't have made such noises. Gregor's mother begins to cry, along with Grete, and calls for a doctor. In all the hubbub, Gregor is calm and optimistic that his family now realizes something is wrong and will take steps to help him. He awkwardly attempts to unlock the door with his mouth, drooling a brown liquid as he does so.
All three sections of the story reach a climax in a moment where intentions are harshly different from outcomes. In this first instance, the crisis occurs because Gregor doesn't yet realize exactly how grotesque and horrible he's become in others' eyes. He's earnestly trying to open the door to explain himself without realizing that his appearance will shock and horrify those he is trying to calm, and that he can't even speak to communicate the things he wants to.
Gregor finally gets the door open, shocking the Chief Clerk, his father and mother. His father weeps. Gregor stays halfway in his room, noticing the rainy weather, the breakfast plates laid out, and a photo of himself when he was in the army.
Gregor behaves in a surprising way. If he were fully human, he'd understand the others' reactions and try to minimize them. Instead, he's distracted by tiny details.
In a long speech, Gregor states his loyalty to his company and asks the Chief Clerk, "Stand up for me in the firm." The horrified clerk backs out of the room. Gregor knows he can't let the clerk leave the house in such a state, so he approaches the clerk, finally dropping from an upright position onto his many legs, which he finds much more comfortable. Gregor underestimates the alarm he's causing his mother and the clerk, only noticing that his mother has spilled the coffee and that the clerk has fled the house.
We see how Gregor's brain, as well as his body, has separated him from humanity. He hasn't put two and two together and understood that no one can comprehend his speech. He doesn't even realize that he's scaring the others, and thinks more of his own comfort. He's not a man's a brain in a cockroach's body, but a merging of the two.
Gregor's father tries to force Gregor back into his bedroom with a cane and newspaper. Gregor has trouble backing up, especially since his father keeps irritating him by saying "shoo." Gregor can't fit through the doorway, but understands that his father wants him in as quickly as possible. He painfully wedges himself into the doorway, staining it, and his father pushes him the rest of the way in and slams the door.
Gregor's father's attitude has also changed remarkably from the beginning of the scene, when he wept in sadness at seeing Gregor. Likely stemming from both prejudices about cockroaches, and from Gregor's irrational, non-human behavior, the father no longer treats him like a son but rather more like he would treat the insect that Gregor now appears to be (and is).