Supernatural's season 10 finale will leave fans even more anxious than last year's Demon Dean reveal.

When Will Rowena Leave Crowley On 'Supernatural'? New PHOTOS Tease Departure

The untitled season finale will have fans white knuckling it through the summer months, eagerly awaiting the start of season 11, according to production coordinator Jason Fischer.

"Just finished reading the finale," Fischer teased on Thursday. "You thought you were on pins and needles last 'Hellatus' ...You haven't seen anything yet."

Wick's Back On 'The 100'! 'Horrible' Sight Greats Jasper & Maya As Finale Begins

It is currently unknown who penned the ominous script. Adam Glass, however, is working on a story for late in the season, if not the actual finale, and it sounds like his Winchester bros. adventure will be just as traumatizing.

"My office today," Glass tweeted in early February, captioning a photo of a tranquil park. "Beautiful outside. But Very bad and dark things happening on my computer. #Supernatural ."

Will Dean's (Jensen Ackles) reignited battle with the Mark of Cain lead him down a murderous path? Cain (Timothy Omundson) believes his protégée will off Crowley (Mark Sheppard), Castiel (Misha Collins), and Sam (Jared Padalecki) - any of which could leave fans gasping as season 10 comes to a close.

Find out more when Supernatural returns to The CW on March 18 at 9 p.m. ET. Click the video below to see a preview for the series' next episode, "The Things They Carried."

Tags: supernatural television the cw