As the book begins, thirty-six-year-old neurosurgeon Paul Kalanithi and his wife, Lucy, an internist, examine his CT scan. Both are anxious. The scan, featuring spinal deformation and liver damage as well as multiple lung tumors, reveals that Paul has a severe form of cancer that will more than likely claim his life. Lucy asks Paul if it could possibly be anything else, but he says no.

The first signs of illness appear six months before this, in the form of severe back pain and rapid weight loss. Paul is reaching the end of his neurosurgical residency at Stanford University, with only one more year before his training is complete. He works long hours and trains hard, leaving him little time for his wife or for other interests, such as literature. Concerned with his chronic health problems, Paul tries requesting an MRI from his primary caregiver. Unfortunately, she is on maternity leave, and he must seek help from the young doctor in her place.

The replacement doctor denies Paul’s request for an MRI, because MRIs are seen as too expensive to use right away. She opts for an X-ray instead, even though an X-ray is less accurate at catching cancer. The X-ray appears without cause for concern, so Paul assumes his ailment is a pars fracture, which is much more common for a man in his thirties than cancer. He and the doctor assume that approaching middle age and overwork might be additional contributors to his symptoms.

Aside from the weight loss and back pain, Paul feels satisfied with his life. Once his training ends, he plans on having children with Lucy and having enough money to buy a catamaran by the sea for weekend vacations. His program director at Stanford tells Paul that he will more than likely be the “number one candidate” for whatever job he desires and that the Stanford faculty will be looking to hire someone with Paul’s qualifications in the near future.

For a while, Paul alleviates his back pain by taking ibuprofen, but he continues to lose weight (even though it does slow) and begins experiencing chest pain a few weeks after the doctor’s appointment. Though both he and Lucy start to suspect cancer, Paul denies the possibility and refuses to share his true fears with Lucy. This culminates during a trip to Dolores Park: Lucy glimpses search results for “frequency of cancers in thirty- to-forty-year-olds” on Paul’s phone screen and presses him to confide in her. He declines, suggesting they get ice cream instead.

This reluctance to communicate frustrates Lucy, and she decides not to come along with Paul on a vacation to see college friends in Cold Spring, New York. She confesses that she has doubts about their marriage and feels isolated; after all, Paul’s neurosurgery training often requires him to leave for work before Lucy wakes up in the morning and return home after she has fallen asleep late at night.

Confused and angry at Lucy’s need to be alone, Paul offers superficial solutions to the marital rift, such as marriage therapy or the promise of more quality time once the hard work of his residency is over in a year, but Lucy insists she needs alone time to think. Paul feels abandoned and wonders if this means the end of their marriage, even going as far as to say to himself that if Lucy is not back home when he returns, he will consider the union over, no matter what she says. While he is on the plane to New York, though, Lucy texts him: she will be back at home...