As usual, Lost's latest season finale left us with as many questions as answers. In anticipation of the show's return on Jan. 21, here's a look at some of the biggest questions.

Ben told Jack he might as well abandon his "very dark" attempt to get back to the island in another plane crash: All six members of the Oceanic Six have to return to the island together. But why?

Season 3 ended with Jack pleading: "We have to go back, Kate." Season 4 explained how the conversation came to be. But will everyone agree to go? Jack: "We made a mistake. ... We were not supposed to leave." Kate: "Yes, we were."

In Season 4, we saw the ship Jin was on explode, and Sun visited his grave. But it may not prove a thing: the gravestone says he died on Sept. 22, 2004, which is the date of Flight 815's crash, not of the ship explosion.

Jack says Locke told him that after he left the island, "some very bad things happened." What happened to Sawyer and the other castaways?

Desmond and Penny are reunited, finally, but does that end their story? Sadly, no. Ben has vowed to kill Penny to avenge the death of his own daughter.

Ben and Charles Widmore agree that Ben isn't able to kill him, which is why Ben has turned his attention to Penny. What makes the old man so unkillable? It can't be all the scotch.

How will 24's Reiko Aylesworth fit into the story? She reportedly plays a smart and professional nature lover looking for Mr. Right. Yeah, we're sure it's that simple.

This logo for Ajira Airlines popped up in a recent Season 5 trailer. Which recently wealthy member of the Oceanic Six might like an airline with a sun logo? We're just speculating.