For a children's series, there's a surprising amount:
* When we find out that Conker is [[spoiler:terminally ill]]. It's a real kick to the teeth when he [[spoiler:dies unexpectedly a couple of scenes later.]]
** Lucy's reaction is sadder still.
* The whole story of Liz and Arthur.
** And finding out that [[spoiler:Arthur tried to drown himself after seeing Liz nursing what he presumed was the product of cheating in his absence.]]
** AND he was going to propose to her that night as well. It really triggers the waterworks when we find out that Liz kept the ring he dropped.
* [[spoiler:David's death.]]
* Gwilanna and Gwendolen's relationship. The crone [[spoiler:took away any freedom the girl had]] and the saddest part is that this is her attempt at love.
* When [[spoiler:Henry Bacon]] dies. AND when [[spoiler:he dies again]] in a parallel universe.