Melinda Ashley has a plan for her life, and a trip to Mars isn't part of it. When she receives a ticket on a spaceliner as a high school graduation gift from her dad, who has business there, she is stunned and has no desire to accompany him. But she has longed for a chance to get to know her dad, whom she has seldom seen, and she's furious when her fiance tries to forbid her from going. She doesn't expect to enjoy the weeks aboard the ship, but her outlook begins to change when she meets Alex Preston, a second-generation Martian colonist who is going home after college on Earth. Alex believes settling Mars is important. He's looking forward to the role he expects to play in the colony's future. Melinda finds this hard to understand, yet she is more and more drawn to him and, while on Mars, to his family. Torn between what she has always wanted and upsetting new feelings, she wonders if she can ever again be content. Ultimately, after she has faced tragedy and sorrow, a terrifying experience on the Martian moon Phobos shows Melinda what really matters to her.