“Yes Men” is episode fifteen of season one of Marvel’s Agents of S.H.I.E.L.D.
At the end of the previous episode, “T.A.H.I.T.I.”, Skye’s life had been saved and Agent Coulson had discovered that the miracle drug that saved Skye, and originally him, was a fluid from the partial corpse of some sort of blue alien (maybe an ice giant, like Loki?).
Lorelei, an Asgardian, and apparently an ally of Loki (according to her Wikipedia entry anyway), had also appeared on Earth.
In this episode Lady Sif, also an Asgardian, visits Earth. I think this is the first episode where they’ve had an actual Marvel supervillainess, and superheroine, in it. Or indeed anyone with the sort of superpowers of the lvel that are seen in the films (Nick Fury doesn’t really count; he doesn’t really have super abilities). Lorelei can enslave men using her voice and touch, hence the title of the episode.
Jasper Sitwell, who appears in The Winter Soldier, also has a cameo in this episode. Which, if you’ve seen The Winter Soldier, is interesting.