A family saga that, at its heart, is a love story. In 1705, Jedediah Truelock won a piece of land on Cape Cod, a peninsula attached to Massachusetts Colony. Thus begins the saga of the Truelock family. The men go off to sea while the women stay home and raise their children. It's a hard life, but they prevail, and by 1768, Lawrence Truelock, Jedediah's grandson, is building a mansion around the cabin his grandfather built for his new bride. Lawrence is a gambler who longs for the good things in life. He improves himself, travels, and marries a Russian noblewoman who gives him a son, Stephen. As Stephen grows, he is often ignored by his father, who spends little time at the mansion he was so eager to build, but it doesn't harden Stephen's heart. As the years go by and Stephen becomes a man, tragic circumstances force him to seek a bride. A family friend tells him about a young woman named Mercy Pruitt. Stephen travels to Philadelphia to meet her, and the two instantly fall in love. They marry and dream of a future together, but destiny has other plans for the newlyweds. A wicked twist of fate brings Mercy's younger sister Rose to live at the mansion, and though others notice how Rose feels about Stephen, kind-hearted Mercy is blind to Rose's machinations as Rose tries to win Stephen away from her sister. Things spin out of control when Rose finds a book of spells in the mansion and plots to use magic to rid herself of Mercy forever, but can she change Stephen's heart with witchcraft? Their Best Years is the history of the Truelock family, their hopes and dreams, and of a love that transcends time.