In The Ten Years, Clara reflects on her tumultuous relationship with her sister Adele, a bond forged in childhood promises and marred by jealousy and tragedy. The story unfolds as Clara recalls the night their mother died, a pivotal moment that solidified their vow to always be together. As the years pass, Clara's life takes a turn when she falls in love with Douglas Foley, a man who becomes the center of her world. However, this new love ignites a fierce jealousy in Adele, who feels abandoned and betrayed by her sister's choice. Despite Clara's assurances that Adele would always be part of her life, the rift between the sisters deepens when Clara marries Douglas, and Adele's emotional instability spirals out of control.