Rip Hunter and his team learned the hard way that no matter how hard they try, the past cannot be changed. But will they still have the chance to change the future or will Rip call off the whole mission and return to his time with his mentor?

The third episode of "Legends of Tomorrow" saw Ray (Brandon Routh) faltering after his attempt to save Kendra failed. Snart's (Wentworth Miller) plan to stop his father from stealing an emerald in the past and consequently destroying their family also failed as the elder Snart was still arrested and sent to jail. And in a moment of anger, Rip (Arthur Darvill) inadvertently revealed to Vandal Savage (Casper Crump) his son's name, a crucial piece of information that the villain will use to hunt down the Time Master's family. While those were hard lessons to learn, the team was able to come together in the end.

However, they have a harder challenge ahead of them as they continue their search for Savage. According to a synopsis for episode 4, when Savage went behind the Iron Curtain in the early 1980s, several nuclear scientists disappeared, prompting the team to head to the USSR in a bid to find Savage's next victim. Ray tries to develop a connection with Valentina Vostock (Stephanie Corneliussen), a striking Russian scientist, but she appears to be immune to his charms. Meanwhile, Stein's (Victor Garber) insistent demand for Jax (Franz Drameh) to push himself to improve leads to frustrations that threaten Firestorm. Sara (Caity Lotz) starts training Kendra (Ciara Renée) at Rip's request.

Comic book fans know Vostock by her other moniker - Negative Woman. But whether she will be introduced as such in episode 4 remain unknown. However, Vostock appears to still be human - and smitten with Snart – in recently released photos from the episode.

The trailer for the episode features another problem for the team, the arrival of Zaman Druce (Martin Donovan), Rip's mentor. The clip shows Rip in the middle of a room, apparently being questioned, as a voice says that he turned his back "on the very institution you meant to serve." Rip tells his mentor that he's trying to save the world. Various scenes show Sara training Kendra, Jax reminding Stein that this mission was "bigger than anyone of us," Vostock kissing Snart and Dr. Stein in pain while holding a flaming orb. The teaser ends with Rip telling the others it's "time to decide whether the future is worth fighting for."

Fans will learn what the team decides on when episode 4 of "Legends of Tomorrow" is aired on Feb. 11.