"High School Musical 4" is definitely happening and production for the film has already started. Aside from being on the hunt for new cast members, rumor has it that certain oldies are coming back to East High.

Reports are now claiming that Zac Efron, who played basketball player and theater geek Troy Bolton, may return to the Disney Channel original film after all. Previous reports have been saying that Efron will not be appearing in the fourth installment due to his hectic schedule.

Efron has been very busy as of late, starring in numerous films including "Neighbors 2," "Mike and Dave Need Wedding Dates," and "Dirty Grandpa." He has also just finished work on "Baywatch," the film reboot of the popular 1989 series of the same name.

More recently, there have been rumors flying around that Efron will be replacing Jamie Dornan on "Fifty Shades Freed." However, it does not seem like there is any truth to them since the film has already started filming with Dornan in tow.

Heads have now turned to the possibility of Efron returning to East High. It is speculated that he will be training the new cast members for "High School Musical 4," accompanied by his real-life ex-girlfriend Vanessa Hudgens, who played Troy's love interest Gabriella Montez in the first three installments.

Given their history, it remains to be seen if the two will agree to work together. Efron was previously absent in the "High School Musical" reunion special, which broke the hearts of many fans.

"High School Musical 4" will welcome a set of new characters to East High, including Erin, a skilled soccer player; Derek, a dancer with a bad boy reputation; Nathalie, Erin's cheerleader best friend; and Tamara, a disgraced former queen bee. The all-new cast will also include Campbell — the captain of the soccer team and a theater buff — who is Sharpay (Ashley Tisdale) and Ryan's (Lucas Grabeel) cousin.

In other news, Hudgens and Tisdale recently had a reunion of sorts at another Disney star's concert. The two real-life friends rocked out to Selena Gomez at the Staples Center a few days ago.

"High School Musical 4" will premiere sometime in 2018.