Elizabeth's sister, Julie, visits Hope Valley in her quest to become a teacher; Lee is made acting sheriff when Abigail and Bill leave town to testify in Gowen's trial; Carson has problems with a traveling tonic salesmen.
Elizabeth mentors Julie, who finds teaching more difficult than she imagined; Abigail has to find a way to convince the railroad to build its depot in Hope Valley.
Jack returns and he and Elizabeth start planning their future. Sparks fly between Carson and a new arrival. Elizabeth teaches her students the difference between facts and speculation, and the town is put on edge when Lee can’t withdraw funds to pay his employees.
Abigail has to figure out how to keep the town's bank thriving. Meanwhile, Elizabeth struggles to understand what troubles one of her students. Rosemary is overzealous in planning Jack and Elizabeth's wedding.
Jack and Elizabeth's plan to get married is put in serious jeopardy, and Bill has difficulties transporting a prisoner.
Jack and Elizabeth's relationship is put to the test. Pastor Frank and Abigail make a decision about their future and Bill helps a young girl solve a mystery.
Elizabeth assigns her students to follow business leaders in Hope Valley; Abigail and the town host two possible investors for the failing bank; and Bill's life is disrupted when A.J. Foster arrives and turns herself in.
Bill is put in jeopardy while transporting A.J. to face trial; Abigail tries to save the town from an investor who will hurt Hope Valley; Carson is faced with a decision concerning his late wife's other sister; Elizabeth tries to reunite a mother and her son.
The widow of Lee's former partner arrives and gives Gowen a chance to run a company again; Elizabeth tutors a new student; the residents of Hope Valley conspire to pull off a surprise. However, Elizabeth receives shocking news about Jack.
Three weeks following Jack's death, Elizabeth, distraught, wonders if she should remain in town. Abigail gives her a letter that Jack wrote to be read in the event of his death. Bill gives her Jack's horse from the Mounties, and the school is renamed in Jack's honor. Elizabeth exhibits strange symptoms, and Abigail suggests that she is pregnant.