Ariel, Bias, & Cody panic when they find a baby who was taken along with Ariel's shopping from the taxi. They tried to return the baby but circumstances forced them to take the baby back to the boarding house, even though there was a prohibition on keeping pets or bringing younger siblings, let alone children, so they had to hide the baby from the boarding house owner. Because they had no experience taking care of babies, they had a hard time taking care of the baby they named Sheyna.
More info
