Song Yubai died of exhaustion in the examination hall in her past life, and after rebirth, she unexpectedly gained the ability to understand baby talk. To save her sick mother, she entered the Gu mansion as a maid, and cured the adorable babies that court nobles were helpless against by "identifying causes of illness through crying sounds." From then on, all court nobles queued up to beg her to babysit. Relying on an account book and a bamboo abacus, she cleaned up inner-courtyard conspiracies, exposed the wet nurse's poisoning, rose from a poor maid to the capital's number one childcare expert, revived the Song family's medical path, and harvested cross-class respect and love in the process of protecting children.