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 | ||
| 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 | |
| Conor O'Donnell | Guest Star | Waiter | |
| Sophie Brown | Guest Star | Baby Anna | |
| Julia Dearden | Guest Star | Maureen Malarkey | |
| Caoimhe Farren | Guest Star | Ms Taylor | |
| Cara Quin | Guest Star | Communion Girl | |
| Bronagh Gallagher | Guest Star | The Commitment | |
| Beccy Henderson | Guest Star | Aisling | |
| Eleanor Methven | Guest Star | Aunt Bridie | |
| James Stockdale | Guest Star | Tomas | |
| Zoe Brown | Guest Star | Baby Anna | |
| Amelia Crowley | Guest Star | Deirdre Mallon | |
| Jay Duffy | Guest Star | Harry | |
| Cara Mailey | Guest Star | Little Girl | |
| Liam Neeson | Guest Star | Chief Constable Byers | |
| Paul Mallon | Guest Star | Dennis | |
| Michael Byers | Guest Star | Officer Lennox | |
| Billy Carter | Guest Star | Mailman | |
| Desmond Eastwood | Guest Star | Benny | |
| Philippa Dunne | Guest Star | Geraldine Devlin | |
| Laurie Kynaston | Guest Star | Philip | |
| Bronagh Taggart | Guest Star | Intercom | |
| 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 |