Everything you need to know about 'Snowpiercer' before watching season 3

• "Snowpiercer" season three premieres today on TNT.
• The dystopian series follows the last of civilization who live on a train to stay alive.
• In season 3, the passengers look for a safe place to finally leave the train.

TNT's sci-fi series "Snowpiercer" returns for its third season today.

The post-apocalyptic dystopian drama, based on the French graphic novel "Le Transperceneige," follows the last of human civilization after Earth becomes a frozen wasteland. The humans live onboard a train called Snowpiercer that constantly moves across the world to keep its passengers warm from the deadly cold outside.

The graphic novel was first adapted into a movie in 2013, that was directed by Oscar-winner Bong Joon-ho. The series takes some of the initial concepts from the movie, such as the train being divided into distinct train classes that reflect their social class and the group at the tail of the train revolting against the unfair system.

However, over the first two seasons, the story has become more complicated. With the first episode of season 3 premiering today on TNT, here is everything you need to know or remember before watching the new season.

The revolution against the rule of Mr Wilford continues in season 3

In season one, we were introduced to our protagonist Layton (Daveed Diggs). He was from the end of the train where people lived in filth and with little food because they weren't meant to be on the train. At this point, the all passengers lived under an authoritarian rule led by Mr Wilford, the creator of the train.

Because of his former position as a homicide detective, Layton was brought to the front of the train to be the train's detective after there had been a number of murders. Using this position, Layton discovered that the train is run by Melanie Cavill (Jennifer Connolly) not Mr Wilford, and thus led a rebellion to form a democracy on the train.

At the end of season one, another train Big Alice, led by the real Mr Wilford (Sean Bean), attached itself to Snowpiercer. Using trickery, Mr Wilford undermined Layton's democracy in season two and took control of Snowpiercer.

At the end of season two, Layton and his comrades escaped Snowpiercer by breaking off the front of the train, vowing to return to save everyone. In the third season, we will see whether Layton's democracy can prevail over Mr Wilford's authoritarian rule.

In season 3, there is also new hope of leaving the train to a warmer world.

In season two, Melanie believed that the Earth is warming after seeing snowflakes. She left Snowpiercer to go to a research facility to test if this theory was true. However, due to Mr Wilford's schemes, by the time Layton and his friends returned to her at the end of the season, Melanie had disappeared. It was presumed that she had died but her mission was a success. She had found that the Earth was warming.

In season three, Layton and his crew will also be looking for a place in the world warm enough for humans to live again so they're not fighting for decreasing resources on Snowpiercer.

The main cast from previous seasons will be returning for season three including Jennifer Connolly who may appear in flashback scenes as Melanie. Also, according to the trailer, a new character will meet the Snowpiercer crew in season three. Emmy award-winning actress Archie Panjabi joins the cast as Asha, a woman who had miraculously survived the cold.

The episode will be coming out on a weekly basis on TNT.