"Agents of S.H.I.E.L.D." is heading for its winter finale episode tonight and the show is bound to bring more action and leave fans wanting for more.

Based on the trailer for episode 10 titled "Maveth," the ongoing fight between Hydra and S.H.I.E.L.D. has been taken to a different planet. Scientists Jemma Simmons (Elizabeth Henstridge) was kidnapped by HYDRA back in episode 9 to get some information on how to open a portal to the other side.

But of course, Iain De Caestecker's Leo Fitz didn't want Simmons to be hurt, which is why he saved her. While the good guys will continue with their mission to save the world, the bad guys will try to bring back an ancient evil through the portal.

In a preview clip released, double-agent Grant Ward (Brett Dalton), who was earlier revealed as a member of HYDRA, was seen with Fitz, demanding him to find the next portal fast. The two got into an argument, but Fitz planned it all along so he could get close and get Ward's gun.

But too bad, he failed at his attempt and Ward threatens that if he won't help find the portal, he'll give Simmons a slow and horrible death. Then one of Ward's soldiers called to the group as he discovered something on the planet, with Ward saying "Hail HYDRA."

According to the Los Angeles Times, speculations suggest that the group discovered a spot where Simmons was or the legendary city of Attilan.

Meanwhile, TV Guide also shared that the midseason finale will bring great surprises, and also the death of a character, which is not considered as the big surprise. What will surprise fans, though, is how this death will be met.

TV Guide reports that the death will be the result of one character making "out-of-character decision." This death should have a long-lasting impact on the series.

"Agents of S.H.I.E.L.D.'s" "Maveth" is expected to be a big episode, which is why fans of the series should tune in today, Tuesday, at 9 p.m. EST on ABC.