"Child of Mine" is the 1034th episode of Casualty and the 30th episode of the 31st series. It was preceded by "Sleeping With the Enemy" and followed by "When the Whistle Blows". The episode was directed by Simon Massey and written by Jessica Ruston. This episode features a guest crossover appearance of Holby City character Mo Effanga, portrayed by Chizzy Akudolu.
Connie makes an effort to show how much she cares, but Grace rejects her. Connie is frustrated when she discovers that Grace hasn't been taking her epilepsy medication. Meanwhile, Grace's friend Hugo is admitted with his dad's girlfriend Keira after they fell from a ladder in a barn. Connie is concerned for Hugo when she thinks he's struggling to cope with the change of Keira being pregnant, and the fact his dad has moved on from his mum. It soon transpires that Keira is struggling with pre-natal depression, and the team talk her through the options available. However, Connie is having troubles of her own when Grace discovers that Connie has slipped the medication into the cake she was eating. In a fit of rage, Grace speaks again, telling Connie that she always could speak but didn't want to because she hated her. Connie tells Grace the feeling's mutual, shortly before having an epileptic fit. Struggling with the prospect of Grace hating her, Connie turns her attention to Hugo, deciding to stay at his bedside as opposed to going home with Grace and Sam.
Meanwhile, Jez tells Iain that he can't afford to take Louise out to fancy restaurants, and Iain tells him to just admit it to her. However, he goes about it the wrong way and Louise is upset that he's cancelled their plans last-minute. Elsewhere, Lily continues to teach Gemma, but is worried for her when it transpires that she has to take a numeracy test in a couple of weeks in order to keep her job.
David returns to work, and Charlie is angered when Max tells him he shouldn't even be there. David puts his resignation letter on Jacob's desk. However, his confidence is boosted when working alongside Dylan in treating Molly Drover. Although she announces that she doesn't wish to be resuscitated, David speaks to her just before her condition deteriorates, and she says she takes it back. David urges them to operate, and eventually Mo Effanga from cardiothoracics is able to save her. At the end of the shift, Robyn lets David hold Charlotte as their friendship grows again, and Jacob hands him back the letter of resignation, unopened.