"In modern-day Mexico, Sitlali is all alone after the death of her beloved abuela. Targeted by a dangerous gang member, she flees to the United States to find her father. The night before her journey, she finds an ancient conch shell on the beach and takes it with her as a memento of home. In 1521, Calizto is trapped in the Aztec city of Tenochtitlan, which is besieged by Spanish invaders. He has fought valiantly, but hope for his people is running...