"Arrow's" primary theme tonight -- "Restoration" -- served not only as the episode's title, but as its anchoring focus. Ra's Al Ghul, Malcolm Merlyn, Damien Darhk, H.I.V.E. -- they've all taken things from Team Arrow. H.I.V.E. took Diggle's brother from him. Ra's Al Ghul took Thea's sanity, Malcom Merlyn took Sara's life. The aftermath and consequences of all these events took Laurel's father from her, lost Diggle's trust in Oliver, claimed the life of Ray Palmer and decimated the bonds of friendship in the original Team Arrow. Now the team has the opportunity to restore what was lost, and in this episode, each character goes on a journey to do just that.

First, Diggle (David Ramsey) attempts to track down the woman who killed his brother, a women named Mina Fayad. Fayad is said to have hired Floyd Lawton/Deadshot to kill Andy Diggle, an operation sanctioned by H.I.V.E. When Fayad arrives in Star City to meet up with Damien Darhk, Diggle ambushes her. His ambush is unsuccessful, because he attacks her without any backup. Oliver (Stephen Amell) attempts to being some restoration to Star City by apprehending an armed robber. He also goes in alone, and ends up getting attacked by H.I.V.E.'s new metahuman hitman Jeremy Tell/Double Down (JR Bourne). Oliver is fast enough to repel Tell's playing cards, but not fast enough to defeat him. Oliver and Diggle both end up back in the Arrowcave wounded, having both their bodies and their pride hurt by attempting to fight these situations alone.

Felicity, knowing the real issue is based on Diggle and Oliver's trust issues, takes this opportunity to lay into them, threatening them with Mirakuru soldiers if they don't get honest with each other. This is Felicity's (Emily Bett Rickards) best scene this season so far. She has watched Oliver and Diggle tiptoe around each other since Oliver came back, and it's making them an ineffective team. Felicity seizes the moment to restore what she calls the "Original Team Arrow." The team that took down Malcolm Merlyn in season one. The team that attempted to thwart The Undertaking. Felicity hasn't seen that team in a long time, and this moment allows her to force the team to reunite for their greater good.

Felicity also gets to restore the tech-based side of Team Arrow by bringing on a new consultant: Curtis Holt (Echo Kellum) -- the future Mr. Terrific. Curtis is a lot like how Felicity was in season one. The addition of Curtis to Team Arrow hearkens back to the show's lighter days -- even Felicity's dialogue in the episode centered around celebrating Team Arrow's early days, whether by drinking margaritas or grabbing a Big Belly Burger. Felicity likely represented the voice of the writers and the fans in the episode, fans who have missed the Original Team Arrow dynamic since it was destroyed by Slade Wilson and Ra's Al Ghul.

The biggest journey of restoration in this episode was Laurel (Katie Cassidy) and Thea's (Willa Holland) trip to Nanda Parbat. After Thea told Laurel about the Lazarus Pit in last week's episode, Laurel was determined to see if the Pit's waters could bring Sara (Caity Lotz) back from the dead. Thea agrees to go with Laurel because she believes Nanda Parbat also holds the key to regaining her own sanity.

Once in Nanda Parbat, Laurel and Thea have to deal with Malcolm Merlyn (John Barrowman) -- the new Ra's Al Ghul and Thea's dad -- and Nyssa (Katrina Law), Oliver's wife (at least technically) and Sara's former lover. This quest for restoration proves to be the hardest of the episode, as both problems -- Thea's sanity and Sara's death -- have to do with powers not defined by the laws of science. For Thea, her hopes of restoration are dashed when Malcolm tells her that her madness cannot be cured by anything but blood lust and death. "The Pit takes a life for a life." Malcolm even sends League soldiers into her room so that she can kill them. This doesn't please Thea, and her condition is left unresolved.

Laurel's passion to resurrect Sara pits her against Nyssa and Malcolm. Nyssa doesn't want Sara to go into the Lazarus Pit because she doesn't trust that her former lover would come back as herself. Malcolm doesn't want Sara in the Pit because he has never seen the Pit used to bring someone back from the dead. Laurel continues to push the issue, fully committed to restoring Sara's life and her family in the process. The only reason Malcolm yields is because he wants to see Thea's mind put at ease for killing Sara in the first place. The ceremony is performed, Sara is brought back to life, and in a surprise move, Nyssa destroys the Lazarus Pit. Now, no matter what happens on future episodes of "Arrow" -- dead is dead.

"Restoration" saw Team Arrow gain a new ally in Curtis Holt, it saw the resurrection of Sara Lance and it saw Team Arrow celebrating their wins over drinks for the first time in a long time. There were also some great Easter eggs dropped in the episode. For instance, Curtis is holding prototype "T-Spheres" at Palmer Tech. These spheres will be a key component to his likely eventual Mr. Terrific persona. Felicity learns some clues about Darhk's "Ghosts" -- they are dead men walking -- missing key components of their genetic code. Lastly, Ray Palmer (Brandon Routh) made an appearance, through Felicity's phone. Everyone presumes that Ray is dead, but every time Felicity is at Palmer Tech her phone starts picking up strange code, including her name. Guessing this a very small Ray, trying to communicate with Felicity through code. Oliver also teased a new Arrowcave, which we'll hopefully get to see next week.