Erin, her cousin Orla, their friends Clare and Michelle, and Michelle's English cousin James navigate their teen years during the end of The Troubles in Derry, where they all attend a Catholic girls' secondary school.
Erin lives with her father Gerry and mother Mary, her baby sister Anna, Mary's younger sister Sarah, Sarah's daughter Orla, and her maternal grandfather, Joe. James is Michelle's cousin; his mother Cathy left Derry for England to have an abortion but gave birth to him and raised him in London. She sends him back to Derry to live with Michelle and her mother Deirdre when she is going through a divorce.
Derry Girls - Across the Barricade Synopsis and Schedule