Dangers are lurking back in Arkadia when the Clarke (Eliza Taylor) and the rest of the gang returns in next episode of "The 100" season 3.

The trailer for the upcoming episode showed the homecoming of Clarke, Octavia (Marie Avgeropoulos) and her brother Bellamy (Bob Morley), Monty (Christopher Larkin), Jasper (Devon Bostick), and Raven (Lindsey Morgan) in their spiritual home. But instead of being welcomed by their peers, the group realized that their spiritual home on Earth has been deserted.

"It's like a ghost town," Octavia said, while Clarke observed that the people in Arkadia suddenly decided to abandon their place. "It's like they just got up and walked away," she said.

But it seems like the group was never alone. Based on the trailer, Raven will be surprised to see someone lurking in the dark. It appears that a group of Grounders managed to infiltrate Arkadia, and they were out there to hunt them down.

The trailer revealed that the Grounders are more dangerous and deadly, and they are really meaning to capture the group at all cost. Raven will become one of the easy targets this season, especially after her physically and mentally challenging battle against A.L.I.E. when she decided to let go of the pill that was being handed out by former chancellor Jaha (Isaiah Washington).

But who ordered the Grounders to capture the group? Could it be A.L.I.E.'s plot to persuade more Sky people to take the City of Light pill so she can further control their minds? Perhaps, the Grounders are tasked to capture Clarke to make her pay for the death of their leaders during the missile attack of the Mountain Men on Tondc.

The official synopsis for the episode titled "Demons" reads:

"Jaha is going to return to Polis, and Murphy will have a surprise encounter. In the meantime, Octavia is going to uncover a clue." 

"The 100" season 3 episode 12 is scheduled to air on The CW on Thursday, April 21.