Between 1999–2002 Mullan made a series of ten television documentaries for Ireland’s TV3 flagship current affairs programme, 20/20, covering the following themes:

1. Sr. Helen Prejean and the Death Penalty
2. Kim Phuc (The little girl burning with napalm in the 1972 iconic Vietnam photograph) visits Richard Moore and Clare Gallagher (who lost her eyesight in the 1998 Omagh Bomb)
3. In the Game of the Father (European Champion boxer, Charlie Nash, and his sons)
4. The Murder of Seamus Ludlow
5. The Dublin and Monaghan Bombings (Part 1)
6. The Dublin and Monaghan Bombings (Part 2)
7. Bloody Sunday: The Right to Truth (Part 1)
8. Bloody Sunday: (Part 2)
9. Dr. Deirdre Killelea of The Panda Foundation (Helping children with ADHD)
10. Millvina Dean, Titanic Survivor