A janitor at the university is cleaning upone of the labs when a mysterious black liquid attacks her. The liquid goes inside her body before the remainder escapes through the vent.
Harry surprises the sisters in the attic, but he isn't wise to the fact they think he's evil. He warns them that the board is prone to tricksters. The sisters plan to deduce who is the evil one.
Macy moves her stuff into their mother's old room; Maggie shows her the bong she made for her as an eight year old.
The Book of Shadows opens up revealing a truth serum potion. They plan to use it on Harry to figure out if he's evil. Mel wants to use the spirit board to communicate with their mother, but Maggie and Macy want to use the truth serum first.
Maggie plans to call Harry "Meghan Markle" so that they can't summon him. She wears gloves so that her telepathy won't work.
At the hospital visiting Angela Wu, the sorority sisters perform a chant to wish her luck. Maggie holds her hands and hears all their thoughts, including Angela screaming inside.
Galvin is joining Macy's new team. He informs her about the cleaning woman being attacked by the black blob.
Maggie hooks up with Brian to get her mind off the hospital visit. However, her telephathy makes the hook up awkward when she can hear him try to keep his mind off the pressure.
Mel makes a date with Niko. The spirit board moves in front of her by showing her nickname.
Macy finds Harry standing over the cleaning woman; he claims that he was there to clear her memory.
Mel is positive that the spirit board is their mother; the board is giving them answers only their mother would know. A hand rips from the board to grab Maggie. Macy uses her powers to flip the board away; it breaks apart.
Macy has hesitations about "the Power of Three" since she feels like the outsider in the household. She doesn't care about communicating with their mother.
When Niko dropped by for dinner, Macy accidentally grabbed the wrong cannister. Niko is so happy being back with Mel.
Galvin calls Macy and informs her that the caretaker has died. Niko mistakenly drinks the wrong container and spills the truth during a police interrogation. Meanwhile, Harry drinks the wrong potion.
Mel grabs Niko from the police stations, but Niko keeps spilling the truth. She reveals that she slept with her former fiancee the previous week. She doesn't want Mel to keep pushing her away.
Maggie blows off hanging out with Lucy to watch over the spirit board. The board moves again and asks her to "release it." Maggie and Mel conduct a spell to release their mother from the board.
Their mother Marisol tells Maggie and Mel that Harry killed her. He plans to do the same to them and steal their powers. Harry deduces the truth; he teleports him and Macy to the attic. They knock him out.
Marisol tells her daughters to find the prism of souls to trap Harry. The artifact is hidden behind a mirror. Maggie can't tell what Marisol is feeling or thinking when she holds her hands.
The sisters search his office and enter the mirror world to look for the prism. They get trapped inside the chamber.
They retrieve the prism after working together to escape the chamber.
Harry warns the sisters that the prism steals powers; Marisol begs the sisters to hand her the prism and kill Harry. Maggie doesn't believe Marisol, but Mel is on the fence.
Mel stabs Marisol and exposes the demon. Maggie uses her phone to create a mirror so that it is destroyed.
Mel and Macy apologize to each other for how they acted. Harry tells Maggie how she can control her powers.
Mel gives Harry the prism so that he can hide it and protect them. Harry didn't kill the caretaker; the demon left an aftereffect that did. Macy gives him a sample to investigate.
Maggie, Mel, and Macy agree to stop their "majority rules" method.
Maggie tells Mel to forget about Niko hooking up with Greta, and Macy to apologize to Galvin. Maggie takes her own advice and officially breaks up with Brian once and for all.
Mel and Maggie clean up Macy's room so that it doesn't feel like a shrine to their mother. They will help her find the answers she needs.
The Elders revealed to Harry that the liquid belonged to "The Harbinger." The Harbinger is the third phase of the prophecy that will lead to the apocalypse. The demon is looking for a vessel.
Angela Wu's eyes open up in the hospital, teasing that she may be the vessel.