“T.A.H.I.T.I.” is episode fourteen of season one of Marvel’s Agents of S.H.I.E.L.D.
In the previous episode, “T.R.A.C.K.S.”, Skye had been shot by Ian Quinn, and had been put into hibernation to stop her from dying. This wasn’t enough, and she’s dying.
When Agent Coulson was dying, or rather was technically dead, he was kept alive (brought back to life) by some unusual technology – and every time the topic was brought up, he mentioned Tahiti. Coincidentally, sort of the title to this episode.
Coulson believes that the same process that brought him back from the dead can keep Skye alive, and wants to take her to the same place. Which results in them breaking a few rules. Oddly, the S.H.I.E.L.D. aircraft in this are rather less technologically advanced than those in the films.
We learn a bit more about Coulson’s experience from when he was killed by Loki.