It's March 15, 1975, and Rosa Rodriguez has just given birth to a premature baby girl, Angelica. Desperate to escape the abusive husband whose beating brought on early labor, Rosa flees Los Angeles to live with her cousin Silvia in San Francisco, but not before conducting a search through the hospital for her daughter's gemela del alma, the child born the same day and time as Angelica. Rosa, an astrologer, believes this child's life will mirror Angelica's, and when she casts her daughter's chart, she is convinced she must find Angelica's cosmic twin because their destinies are complicated. Eighteen years later, it's June, 1993, and Stephanie Bengochea and Jazmín Valdez, best friends since age five, share everything: the same birthday, March 15, 1975, the same appearance, and the same best male friend, Pedro Garcia. After Jaz and Steph graduate from high school, they leave their hometown of Pleasant Valley to attend different colleges, only to discover their paths inexplicably parallel one another's. Yet when both become pregnant the night of their twentieth birthday, free will takes over. Jaz decides to keep her child when her college boyfriend, Martin Donahue, the third, proposes, while Steph breaks up with hers after aborting their child. Steph moves home to help with her family's restaurant because her mother is injured, and when she marries Pedro it shatters Jaz and Steph's sense of sisterhood and pushes the once inseparable friends apart. Meanwhile, in San Francisco, Rosa believes her prayers are answered when she meets Jaz. Thanks to a friend in the SFPD, Rosa knows a young woman named Stephanie Bengochea shares Angelica's birthday, so imagine her surprise when she discovers the young mother across the street is Steph's friend and shares Steph's birthday. Beware the Ides of March, Rosa decides, as she trades daycare with Jaz in exchange for organization of her computer-based business astrology firm called Millennial Fears. The Y2K has the superstitious dotcom crowd in San Francisco logging on for advice, and while Jaz and Rosa refuse to succumb to the dread that plagues their customers, they learn that life can't be plotted out, that the tension between belief and superstition, faith and knowledge, friendship and love, are what will allow them to discover what their destinies should be.