Ep 6. Lost Souls

Oliver and Felicity are still trying to figure out how to get Ray Palmer, the Atom, back after he was shrunk down and disappeared at the end of season three. Felicity, feeling guilty for not being able to help her friend, is obsessively working on finding a solution while Oliver is trying to balance his life as the Green Arrow and his newly-elected role as mayor of Star City.

Meanwhile, Laurel is dealing with her own guilt over the fact that she and Oliver kept Sara's resurrection a secret from the team. She confides in Thea, who seems to be dealing with her own personal crisis as she struggles with the fact that she is no longer under the influence of the Lazarus Pit but is still dealing with the aftermath of its effects.

As Felicity continues her work, she discovers that Ray is stuck in a micro-world along with a group of other scientists. Oliver and the team, with the help of a newly-released villain, must go into the micro-world to rescue Ray and the other scientists before it's too late.

Meanwhile, Diggle is trying to deal with his own personal crisis as he discovers that his brother, who he thought was dead, is actually alive and working with the enemy. He struggles with whether or not to trust his brother and how to handle the situation.

As the team ventures into the micro-world, they face new challenges and obstacles, including the return of a familiar villain. Ultimately, they must work together to rescue the lost souls trapped in the micro-world while also dealing with their own personal demons.

The episode ends with a cliffhanger, leaving viewers wondering what will happen next and how our heroes will deal with the challenges ahead.