SPOILER WARNING: This article contains major spoilers for "Into the Void," The Flash Season 6 premiere.
The Flash must die. In "Into the Void," the Season 6 premiere, the Monitor appeared to Barry Allen and Iris West-Allen with some terrible news. "Crisis on Infinite Earths" has moved up from 2024 to 2019, and Barry will have to sacrifice his life much sooner than they anticipated in order to save the mutliverse.
Throughout the episode, Barry and Iris grappled with grief over their daughter Nora's disappearance. Iris spent the premiere chasing her purple jacket, which she is destined to pass down to Nora, after Joe accidentally threw it away. In the end, Barry installed it in the Time Vault, in the same display that once held Reverse-Flash's costume. The Monitor appeared to them as Barry showed Iris this memorial.
"What do you want?" Barry demanded, to which the Monitor replied, "For your universe to survive."
Iris quickly realized the Monitor was the reason why the plinth -- along with Nora's final message to them -- stopped working. "The plinth!" she cried. "You destroyed it. You destroyed Nora's message!"
"An unfortunate side effect," the Monitor acquiesced. "But I needed to discourage you."
"From doing what?" Barry shot back.
"Hoping. Your determination is boundless, Flash," the Monitor explained. "It is one of your greatest qualities, but you cannot avoid the coming Crisis."
"Barry has five years before he vanishes," Iris insisted.
"No longer," the Monitor revealed. "December 10, 2019. On that day, he will answer the call and make the ultimate sacrifice. Soon, this world will fight for the fate of all the known universes."
"I'm not going to leave my family," Barry retorted. "There has to be a way to stop what's coming."
"I am sorry," the Monitor said. "But events have been set into motion that you cannot possibly comprehend."
"I don't need to understand them! Just tell me what I can do," Barry yelled back.
"To survive? You can't. In order for billions to survive this coming Crisis, The Flash must die," the Monitor concluded, and the episode cut to the credits.
Marv Wolfman and George Pérez's Crisis on Infinite Earths comic book famously featured the death of Barry Allen's The Flash. In the world-altering maxiseries, he sacrificed himself by running so fast to save all of reality that he disintegrated into the Speed Force. A similar death was teased in "Elseworlds," when the Scarlet Speedster and the Girl of Steel ran around the world to slow down time, but Oliver Queen struck a deal with the Monitor to save both their lives.
However, it seems that deal doesn't apply to the upcoming "Crisis on Infinite Earths" crossover. Per the Season 6 trailer, Team Flash will spend the season trying to save Barry from this fate. The Monitor's visit will likely kick that plan into high gear.
Airing Tuesdays at 8 p.m. on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanagh, Jesse L. Martin, Danielle Nicolet and Hartley Sawyer.