Blackwell tells Cassie she can use her dark magic to go back in time and see where Adam's grandfather (Chad Willett) hide it.

It's also revealed to Cassie and Diana that Blackwell planned for all the six pregnancies of their parents so the kids could grow up together and he would be able to build his own Circle.

They follow him to a place where he meets Eben (Sammi Rotibi) and they see that Nick is trying to exchange the crystal with the demon he has inside him because it keeps him alive.

In the meantime, Faye (Phoebe Tonkin) invites Jake to the prom despite the fact that he stood her up two years earlier.

Dawn (Natasha Henstridge) is trying to warn Charles after her failed attempt to stop Blackwell but she doesn't have much of luck.

The encounter leads to Melissa being the one who kills Nick to save Jake, Blackwell getting the last crystal and Eben kidnapping Faye.

"After last week’s chase for the crystals, “Prom” slows things down to idle, passes through the ol’ navigational buoys of finale set-up, and then accelerates into a whole series of emotional revelations, confrontations, and the kidnapping of everyone’s favorite character.

"Secret Circle isn’t perfect, but over the past 5 or 6 episodes the show has found a nice groove and was able to course correct some of the major problems with the first half of the season.