"My Journey to Lhasa" is the true account of Alexandra David-Neel's visit to the city of Lhasa, Tibet in 1924 at a time when foreigners are forbidden to enter. Disguised as a Tibetan pilgrim and traveling with her adopted son, a native Tibetan, she succeeds in eluding the Tibetan authorities during eight months of travel and two months living in Lhasa.

David-Neel is a student of Tibetan culture and religion and has previously spent many years in learning and observing, including a period living in western Tibet where she was the guest of the Tashi Lama, an important religious figure, until her presence was discovered and she was forced to leave the country. It is partly with a sense of revenge, she writes, that she develops the plan to cross into central Tibet to the largest city, Lhasa, located in the heart of the country.

The book begins as David-Neel and Lama Yongden enter from China into part of Tibet still under control of the Chinese after a Tibetan uprising. Here foreigners are allowed to travel, but as they cross into territory controlled by the Tibetan government, they assume the identities of religious pilgrims. David-Neel darkens her face with charcoal and cocoa and poses as Yongden's aged mother. Despite several close calls when her identity as a foreigner is nearly discovered, the pair manages to reach Lhasa after several months of dangerous travel.

Although they travel armed with revolvers and carry some modern objects such as spoons and a compass, the pair dare not reveal these item to anyone because they would ruin their disguise as poor native pilgrims. They take on the role completely, and beg for food and shelter along their way in the manner of other pilgrims.

The journey to Lhasa is treacherous. Bands of robbers roam parts of the country preying on pilgrims and other travelers. The region is mountainous and they are traveling in winter, and must hike through ice and snow. At one point they go several days without food when extreme weather and an injury to Yongden's ankle stop their progress. They travel without maps through regions that have never even been mapped, relying on the sometimes shaky advice of the native Tibetans on the best paths to lead them to Lhasa.

They stay in Lhasa for two months, arriving at the time of the New Year. David-Neel's command of the language and customs allow her to continue to pass as a native. She and Yongden then leave Lhasa, passing quickly westward to the frontier of British-controlled Bhutan. The book ends as she contacts a British representative and reveals she has just crossed Tibet through Lhasa, the first western woman ever to have done so.