'Agents of SHIELD' Returns to TAHITI

02/02/2018 10:00 pm EST

Tonight's episode of Marvel's Agents of SHIELD called back to the series' very first mystery.

SPOILERS for Marvel's Agents of SHIELD Season 5, Episode 10, "Past Life", follow.

Back in the first season of Marvel's Agents of SHIELD, the big mystery was how Phil Coulson, who was killed by Loki in Marvel's The Avengers, was once again among the living. At the beginning, the only thing fans knew for sure was that SHIELD had done something to Coulson, and they did not want Coulson to know about it.

Coulson believed he had been on a long vacation in Tahiti. Only later did he find out it was TAHITI, a secret project buried deep within SHIELD. Nick Fury had greenlit the project, which used Kree DNA and technology, to develop a means of bringing a fallen Avenger back to life. That's exactly what he did to Phil Coulson.

Naturally, the Kree themselves have similar technology, and Kasius has been using it to cruel effect. He breeds and trains Inhumans to sell as slaves, and if they die in the process, he uses the TAHITI technology to revive them.

The use of this technology isn't limited to Inhumans. Kasius also used the technology to revive Tess, who was murdered a few episodes ago. He did this to send a message to the increasingly restless humans, reminding them that he is a god on the Lighthouse.

It turns out Kasius had another special project. Kasius previously teased that he had a seer informing him of SHIELD's actions. It turns out this seer is Yo-Yo from further along in her own timeline. Yo-Yo died and was revived as a captive of Kasius. She's been killed and resurrected several times over. Kasius brings her back to life whenever he needs information. Most recently, he's been using her for her memories of when she traveled to the future, using that information to stay ahead of SHIELD's plans.

We also learned something new about TAHITI's technology. Apparently, it works on humans because they have a relatively simple biology. It does not work on Kree because their physiology is much more complex than a human's. This is revealed when Kasius wants his doctor to revive Sinara, but the doctor explains it simply can't be done.

Marvel's Agents of SHIELD returns to ABC on March 2nd.

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