I'll Meet You at Three Forks takes place in the Rocky Mountains circa 1820. It is the adventurous tale of a young mountain man, Clinton Jeffries, who, while trapping for beaver, is set upon by a party of Blackfeet. He escapes but during the attack, he is severely wounded by an arrow, which is imbedded just above his knee. His trapping partners take him to a friendly group of Indians who nurse him back to health. The arrowhead, however, is lodged deeply in the bone and must be removed by a surgeon.
Knowing that he will be crippled for life if it isn't removed, Jeffries decides to return to civilization (St. Louis) to seek medical help. It is on this return journey that he unexpectedly meets Storm, a Piegan Indian woman. She is traveling with her sister and her sister's husband, Ned. They explain to Clint they are fleeing a hostile group who are after Storm. They ask where he's going and if they might accompany him. Clint agrees and together, they set out to find the Missouri River.
Through their time together, Clint and Storm develop a deep friendship, which eventually leads to them falling in love. As they near the Missouri, a series of unfortunate incidents causes them to become separated. This leaves each one believing the other has been killed. They had, however, promised each other that if they ever separated they should meet at the headwaters of the great river - at Three Forks. After searching for one another and finding nothing, both are grief stricken so they each go their separate ways. Clint goes down-river to St. Louis while Storm travels up-river with her sister and Ned.
Besides having his leg mended in St. Louis, Clint meets an old Indian and saves him from a crowd of men who want to tar and feather him. The Indian becomes his lifelong friend. To get back to the mountains, they sign on with a keel boat crew as meat hunters. It is then that Clint learns Storm may still be alive. This launches him on a relentless, decades-long search to find her.
In a conflict with rivermen, Ned and Storm's sister are killed, leaving her to fend for herself. Being pregnant with Clint's child, she faces many hardships on her own. In her most urgent time of need, she meets and is helped by a Spanish trapper, Armand Velaquez. He is good to her and she appreciates all he does but she never forgets the love she experienced with Clint.
The book does not deal strictly with Clint and Storm and their ageless love affair. Moreover, it weaves a fabric of frontier life and brings to bear, the harsh truth that death was no stranger to the people of the mountains. Also, it illuminates the many characters whom Clint and Storm encounter along their way. It is an exciting story, sometimes amusing, sometimes sad. It is, however, realistic in its descriptive narrative.