The mystery surrounding the benefactor finally unravels on the latest episode of MTV's "Teen Wolf." Entitled "Perishable," the episode weaves the storyline of Beacon Hills police deputy Jordan Parrish, who was listed on a supernatural dead pool but did not know of any paranormal powers he possessed.

In the opening scene, Parrish wakes up handcuffed inside his police car, while another police officer Haigh pours gasoline all over the patrol car. Although Parrish pleads for his life, Haigh ignites the car with deputy Parrish inside.

The next scene shows the killer in the police station along with Sheriff Stilinski, when a burned Parrish bursts into the station and confronts Haigh for trying to kill him. Later, Scott McCall and other supernatural teens ask Parrish what he is, but the deputy isn't sure what is different about him.

Lydia, in the meantime, has been digging into her late grandmother's life after discovering she was aware of people with para-psychological powers like Lydia. Lydia said her grandma was obsessed with studying these people, including Meredith, a young Eichen House psychiatric inmate that the teens know.

At Beacon Hills High, the season opener lacrosse bonfire is gearing up to be a huge drinking party. Everyone is excited about attending, except for new wolf Liam, who has been struggling to dealing with his new double life. Once the party is underway, Liam and coyote Malia decide to escape their problems temporarily by drinking.

When Scott reminds them that as supernatural healers, they never feel the effects of alcohol, they seem disappointed. However, both Malia and Liam begin to lose their balance and feel woozy.

Stiles and Lydia decide not to go to the bonfire and instead try to crack the key code for a note left by Lydia's grandmother. After her pet name for Lydia, Ariel, unlocks the information, the two realize it is a list of people believed to have killed themselves at Eichen House.

They rush to the psychiatric treatment center and ask an orderly, Brunski, to look at the deceased's records for similarities. While Brunski shows them to the files, he immediately stuns both of them and ties them in the basement of Eichen House.

With the bonfire still underway, the wolves are still not sure why they are feeling drunk. Scott, who has also grown weak despite staying sober, realizes that the music playing at the party is causing their disorientation.

Armed officers pull the teens into school, where they prepare to light them on fire. Just as the flame is about to be flicked onto them, Derek and his recent romantic interest Braedan appear and subdue the captors.

While Stiles and Lydia are tied, Brunski admits to killing many people at the psych hospital and making them appear to be suicides. He even admits to killing Lydia's grandma. However, before he can harm either of his current victims, deputy Parrish arrives and shoots Brunski.

It seemed as though Brunski was the benefactor, but in his dying breaths reveals it was Meredith, who really hadn't died.

"Teen Wolf" airs Mondays at 10/9c on MTV, except for next week's episode, which will premiere Sunday immediately before the Video Music Awards.