Watch the nostalgic 'Harry Potter 20th Anniversary: Return to Hogwarts' trailer

The clip begins with a line from Harry Potter and the Order of the Phoenix, when Harry Potter (Daniel Radcliffe) was teaching his friends how to produce the Patronus charm in this scene: "Think of a powerful memory. Make it the happiest you can remember."

From there, present-day Emma Watson says, "It feels like no time has passed and loads of time has passed," as she embraces Tom Felton, who played Draco Malfoy for the duration of the series. (Watson, of course, was the fearless Hermione Granger.)

Rupert Grint, known best as Ron Weasley, asserts that now "is the perfect time to sit down with everyone and reminisce, and then Radcliffe confesses his biggest fear from the end of the eight-film Harry Potter franchise: "The thing that scared me the most the implication that the most meaningful thing in our life was done, and there's something so joyous about seeing everyone and be like, 'It wasn't, though.'"

Helena Bonham Carter shares that her favorite memory from her four-film arc as the evil Bellatrix Lestrange was "when I had to pretend to be Hermione pretending to be Bellatrix," which happened in the franchise's last installment Harry Potter and the Deathly Hallows: Part 2.

Ralph Fiennes also explains the initial hesitation he had about portraying Lord Voldemort.

Ultimately, however, it would appear the most emotional bits will come when Grint, Radcliffe and Watson reminisce along in the Gryffindor common room. 

"When things get really dark and times are really hard, there's something about Harry Potter that makes life richer," Watson explains. And as Watson gets teary-eyed, Grint adds, "It's a strong bond that we'll always have. We're family, and we will always be part of each other's life."

The reunion special will additionally feature director Chris Columbus and cast members Robbie Coltrane, Gary Oldman, Imelda Staunton, James Phelps, Oliver Phelps, Mark Williams, Bonnie Wright, Alfred Enoch, Matthew Lewis, Evanna Lynch, and more.

Return to Hogwarts commemorates the 20th anniversary of the theatrical release of Harry Potter and the Sorcerer's Stone, the first movie in the iconic franchise adapted from J.K. Rowling's novels.

See the previous teasers below.