"Never Say Never" is the 963rd episode of Holby City and the eighth episode of the 21st series. It was preceded by "Good Side" and followed by "Guts". This episode was directed by Waris Islam and written by Nick Fisher and Patrick Homes. This episode marks the guest return of cardiothoracic registrar Zosia March, portrayed by Camilla Arfwedson, who last appeared in the series 20 episode "The Prisoner".
Facing complications in theatre, Jac is forced to page the hospital's new locum cardiothoracic registrar; she is shocked to discover that it is Zosia. In her office, she questions Zosia about her motives for returning to Holby given her time at Yale. Zosia claims that it didn't work out in America and wants to apply for the position of senior registrar - Frieda's job. Suspicious, Jac grills Hanssen who tells her that Frieda had been granted indefinite compassionate leave and there is a possibility that she may not return.
Her suspicions increase when Jim Mullins, one of Frieda's old patients and her boxing trainer, is taken up to Darwin and reveals that she recently went to his gym. By the end of the day, Jac starts to trust Zosia and offers her the senior registrar post. After Jac receives a message from Frieda bidding farewell to her, Zosia drops a bombshell - she is five months pregnant.
Meanwhile, Ange struggles to convince Holly's parents that there is no hope of recovery. The situation becomes more difficult when they learn of a dubious institute in America offering experimental treatment. After Essie unintentionally validates their stance and they begin making posts on social media, Hanssen fears the prospect of a media storm. Later, Ruth goes to the press.
On AAU, Donna and Zav argue over him setting a bad example for her girls and agree to keep clear of each other for the entire shift. However, they are forced to work together when they are pitted with a patient requiring hours of treatment. Later, Zav agrees to do better and the couple reconcile.