Series "Foundling3" is the sequel of the previous two, "Foundling" and "Foundling2". The events take place when the daughters of Anna and Nikita turn one. While at the pediatrician's office, Anna and her daughter meet Gosha. He just started investigating the case of the "foundling": an infant was found in a stroller with a note attached: "I beg you. Save my son". An infant is assigned to a foster care for the newborns. Doctors find out there is a heart deficiency, and an infant requires expensive surgery. Anna tries to persuade her husband to adopt sick boy to save his life. Along that story Gosha finds the baby's mother who is being followed by her conning husband. This story, of course, has a happy ending. The mother of an infant is found. Gosha saves her and her child. Anna provides great support for the child, who feels like her own, to get the medical assistance he is in great need for.