I'll add notes when I re-watch this series.
Do not watch this without respecting the Buffy the Vampire Slayer and Angel viewing order.
A vampire, cursed with a soul to be immortally haunted by his past, hopes for absolution by fighting the damned.
An astonishing series. The characters and story are outstanding. While built upon/within the Buffy the Vampire Slayer universe, it has a different and significantly more adult story line. I would say that this series is better than its parent, but Buffy is mandatory and still enjoyable viewing to get to this one.
Set in the universe of Buffy the Vampire Slayer - (1997 show), sharing significant-enough elements that crossover-viewing is largely considered mandatory. See Buffy the Vampire Slayer and Angel viewing order.