The CW has shifted the weekly DC TV schedule to accommodate the Arrowverse crossover, so here’s what you need to know if you want to tune in.

Instead of “Supergirl,” the “Elseworlds” crossover will kick off Sunday at 8 p.m. EST with “The Flash.” “Arrow” will air as usual on Monday at 8 p.m. EST. Finally, “Supergirl” will wrap up the crossover on Tuesday at 8 p.m. EST, switching spots with the speedster.

To watch the big event, fans can tune in on The CW each night. That’s your only option for watching live. There is no official live feed to watch online, but the episodes will be available on the CW website and app as well as On Demand the day after they air.

It seems like the Arrowverse crossover is an event that fans will want to watch live. The special episodes will start out with Oliver Queen/Green Arrow (Stephen Amell) and Barry Allen/The Flash (Grant Gustin) switching lives. Oliver is recognized as the speedster and wakes up to Iris (Candice Patton) making him pancakes while Barry is thought to be the archer and trains with Diggle (David Ramsey).

when and where to watch Elseworlds
"Elseworlds" is the three-night Arrowverse crossover between "Supergirl," "Arrow" and "The Flash." Jack Rowand/The CW

Oliver and Barry know that they’ve been messed with, and after STAR Labs comes up empty, they look to Kara Danvers/Supergirl (Melissa Benoist) for help. While on her earth, they meet Clark Kent/Superman (Tyler Hoechlin) and Lois Lane (Elizabeth Tullock).

That’s not the end of the superheroes, though. The vigilantes will also head to Gotham City where they’ll meet Kate Kane/Batwoman (Ruby Rose). They will also happen upon a different Barry Allen, played by John Wesley Shipp.

Obviously a group of heroes this big needs at least a few villains. Nora Fries (Cassandra Jean Amell, wife of Stephen Amell), the wife of Mr. Freeze, will appear. The major villains, however, will be Dr. John Deegan (Jeremy Davies), an Arkham Asylum doc, and The Monitor (LaMonica Garrett). Fans will have to tune in to see how much trouble they cause.

Do not expect any two-hour installments of “Elseworlds.” “DC’s Legends of Tomorrow” is sitting out for the crossover this year while “Black Lightning” is technically not part of the Arrowverse. Both will air new episodes this week following parts 2 and 3 of the event.