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