"Firefly" Season 2 is back and will reveal why longtime friends Tally (Katherine Heigl) and Kate (Sarah Chalke) have broken up and are no longer on speaking terms. As the drama reaches its final episode in the first part of its second season, it continues to flash back to the late 1970s as teenager Tully (Ali Skovbye) and teenager Kate (Roanne Curtis) are involved in various adventures and troubles.

The show also returns to the 1980s, where young adult friends juggle careers and love. Kate begins a relationship with Johnny (Ben Lawson), eventually marries, has a daughter, and divorces.

Meanwhile, Tally becomes a very successful talk show host like Oprah. In Season 2 of "Firefly", Kate suffers the painful aftermath of Johnny's coverage of the Iraq War.

Tully faced a lawsuit after leaving the show and demanded answers about her birth father, despite Hippie Mom's objections.

Click here to watch "Firefly" Season 2.

"Firefly" Season 2 Part 1 premieres on Friday, December 2 at 3:00 am ET/12:00 am ET/8:00 am PT/7:00 pm ET.

Nine episodes will be available simultaneously. The second part of season 2 will be released in 2023.

At the beginning of the Season 2 trailer for "Firefly", Tully says to Kate: "I'm not going to let you go. Kate replies, "I swear on my heart." But as we know, this promise is not kept and something tears them apart in the future.

The rest of the trailer sneaks in teenagers Tally and Kate's hitchhiking adventures, Kate and Johnny's giggly relationship, and Tally making a documentary about her father.

The cast of "Firefly" Season 2 features Katherine Heigl as Tully and Sarah Chalke as Kate, as adults in the 1980s and 2000s time periods.

They will be joined by Ali Skovbye as Teen Tully and Roanne Curtis as Teen Kate.

Ben Lawson is Johnny Ryan, Kate's husband and Tully's producer.

Other cast members include:

"Firefly" Season 2 adds several new cast members. Ignacio Cericchio ("Lost in Space") will play Danny Diaz, a brash and cocky sportscaster who will be a breathtaking pairing with Tally.

India de Beaufort ("Zoe's Unusual Playlist") plays Charlotte, a quiet girl aspiring to be a journalist in 1985 Seattle.

Greg Germann ("Grey's Anatomy") plays Benedict Binswanger, a descendant of a powerful logging family who ran for governor of Washington State in the 1980s.

Jolene Purdy ("White Lotus") is Justin Jordan, a hilarious talent agent who works with Tully.