WARNING: The following contains major spoilers for "Death of the Speed Force," the latest episode of The Flash.
Like the episode title suggests, "Death of the Speed Force" dealt with exactly that: the Speed Force's demise.
In the latest episode of The Flash, Barry Allen discovered the Speed Force was dying when Wally West returned to Central City with concerns about the entity. He learned he accidentally triggered this when he used the Spectre's power to enter the Speed Force during "Crisis on Infinite Earths" -- and now, he and Earth-Prime's speedsters are facing major consequences.
When Barry entered the Speed Force for the last time, he found it on its death bed. The entity had assumed the form of his late mother Nora, who appeared gravely ill. Barry instantly blamed himself for this and promised to fix his mistakes.
"You didn't hurt me," the Speed Force said.
"I attacked you," Barry replied, referencing a moment from the midseason finale when he lashed out at the Speed Force under Bloodwork's influence. "Don't you remember?"
"That's not why I'm dying," it revealed. "A few months ago, a substance entered the Speed Force -- something that we had never encountered before. We tried to contain it, but it contaminated us. It upset the balance of our energies... It is infernal power, beyond the laws of our nature."
"During Crisis, I made the Spectre give me his energy so I could enter the Speed Force again," Barry confessed, putting his head in his hands. "I am responsible. I did this. I killed the Speed Force." With that, he turned to it again. "I didn't know! I never would have -- I'm sorry -- I didn't know!"
"Barry Allen, we forgive you," the Speed Force said, taking his hands. "You did the right thing. You saved our universe. You never could have foreseen what that cost. You only have a few steps left until we're gone from you entirely, but I know you will use them well. The lightning chose you, and it was the best decision that we -- I -- ever made. You showed us the greatest force of all. I love you. I love you, my beautiful boy."
With a final gasp, the Speed Force died, leaving Barry in tears. Though he was the only one present when it happened, he wasn't the only one to sense its passing. Wally and Reverse-Flash also felt the end of the Speed Force. What's worse, the Speed Force's demise means Barry and Wally are running on borrowed time; they both only have so much super speed left before it's gone for ever.
"From what I can figure out, we still have a residual amount of Speed Force inside us, but the more we use up, the less we have left," Wally later explained to Joe.
"Until it's gone forever?" Joe asked. With tears in his eyes, Wally could only nod in response.
However, Barry hasn't lost hope just yet. He was inspired to look into alternate ideas to maintain his speed -- up to and including creating his own Speed Force, like Thawne did with the Negative Speed Force. As Cisco and Caitlin brainstormed some solutions, Barry revealed his true intentions.
"Thanks, guys, but I want your help with something else," Barry admitted. "I've been thinking about what Thawne said... how he built his own power source: the Negative Speed Force. If he can make one, then so can we. I need your help to build an artificial Speed Force. That's how I can get my speed back."
Even as Team Flash devises a way to create a new Speed Force, Barry will have to come up with a new approach to heroism. After all, he no longer has an unlimited supply of super speed. He will have to budget his remaining Speed Force, which means he can't run into situations half-cocked. With the looming threat of Mirror Master and the return of Reverse-Flash, Barry better hope his friends come up with something fast.
Airing Tuesdays at 8 p.m. ET/CT on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanagh, Jesse L. Martin, Danielle Nicolet and Hartley Sawyer.