We return to Derry a year on, in the week of the Good Friday Agreement referendum, as the gang prepare for their final school year and Erin and Orla's 18th birthday.
| Name | Type | Role | |
|---|---|---|---|
| Lisa McGee | Writer | ||
| Art Campion | Guest Star | Father Peter | |
| Francis Mezza | Guest Star | Dee | |
| Donna Traynor | Guest Star | Donna Traynor | |
| Kevin McAleer | Guest Star | Uncle Colm | |
| Vanessa Ifediora | Guest Star | Laurie | |
| Mya Rose McAleese | Guest Star | Baby Anna | |
| Clara Geraghty | Guest Star | Communion Girl | |
| Ardal O'Hanlon | Guest Star | Eammon | |
| Leah O'Rourke | Guest Star | Jenny Joyce | |
| Brenock O’Connor | Guest Star | Jon | |
| Sophie Brown | Guest Star | Baby Anna | |
| Conor O'Donnell | Guest Star | Waiter | |
| Julia Dearden | Guest Star | Maureen Malarkey | |
| Cara Quin | Guest Star | Communion Girl | |
| Caoimhe Farren | Guest Star | Ms Taylor | |
| Bronagh Gallagher | Guest Star | The Commitment | |
| Beccy Henderson | Guest Star | Aisling | |
| Eleanor Methven | Guest Star | Aunt Bridie | |
| Zoe Brown | Guest Star | Baby Anna | |
| James Stockdale | Guest Star | Tomas | |
| Amelia Crowley | Guest Star | Deirdre Mallon | |
| Cara Mailey | Guest Star | Little Girl | |
| Jay Duffy | Guest Star | Harry | |
| Liam Neeson | Guest Star | Chief Constable Byers | |
| Paul Mallon | Guest Star | Dennis | |
| Michael Byers | Guest Star | Officer Lennox | |
| Desmond Eastwood | Guest Star | Benny | |
| Billy Carter | Guest Star | Mailman | |
| Philippa Dunne | Guest Star | Geraldine Devlin | |
| Bronagh Taggart | Guest Star | Intercom | |
| Laurie Kynaston | Guest Star | Philip | |
| Chelsea Clinton | Guest Star | Chelsea Clinton | |
| Claire Rafferty | Guest Star | Miss Mooney | |
| Serena Terry | Guest Star | Officer Reid | |
| Ava Grace McAleese | Guest Star | Baby Anna | |
| Conor Lowry | Guest Star | Young Boy | |
| Robert Calvert | Guest Star | Jim | |
| Michael Lennox | Director |