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 | ||
| Ardal O'Hanlon | Guest Star | Eammon | |
| Ava Grace McAleese | Guest Star | Baby Anna | |
| Leah O'Rourke | Guest Star | Jenny Joyce | |
| Francis Mezza | Guest Star | Dee | |
| Sophie Brown | Guest Star | Baby Anna | |
| Julia Dearden | Guest Star | Maureen Malarkey | |
| Vanessa Ifediora | Guest Star | Laurie | |
| Cara Quin | Guest Star | Communion Girl | |
| Mya Rose McAleese | Guest Star | Baby Anna | |
| Bronagh Gallagher | Guest Star | The Commitment | |
| Beccy Henderson | Guest Star | Aisling | |
| Zoe Brown | Guest Star | Baby Anna | |
| Brenock O’Connor | Guest Star | Jon | |
| Conor O'Donnell | Guest Star | Waiter | |
| Amelia Crowley | Guest Star | Deirdre Mallon | |
| Cara Mailey | Guest Star | Little Girl | |
| Caoimhe Farren | Guest Star | Ms Taylor | |
| Liam Neeson | Guest Star | Chief Constable Byers | |
| Paul Mallon | Guest Star | Dennis | |
| Eleanor Methven | Guest Star | Aunt Bridie | |
| Desmond Eastwood | Guest Star | Benny | |
| James Stockdale | Guest Star | Tomas | |
| Philippa Dunne | Guest Star | Geraldine Devlin | |
| Bronagh Taggart | Guest Star | Intercom | |
| Jay Duffy | Guest Star | Harry | |
| Chelsea Clinton | Guest Star | Chelsea Clinton | |
| Claire Rafferty | Guest Star | Miss Mooney | |
| Michael Byers | Guest Star | Officer Lennox | |
| Conor Lowry | Guest Star | Young Boy | |
| Billy Carter | Guest Star | Mailman | |
| Robert Calvert | Guest Star | Jim | |
| Art Campion | Guest Star | Father Peter | |
| Laurie Kynaston | Guest Star | Philip | |
| Donna Traynor | Guest Star | Donna Traynor | |
| Kevin McAleer | Guest Star | Uncle Colm | |
| Serena Terry | Guest Star | Officer Reid | |
| Clara Geraghty | Guest Star | Communion Girl | |
| Michael Lennox | Director |