What. An. Episode.
Coulson and his team are targeted after S.H.I.E.L.D.'s collapse due to Hydra's infiltration, which was exposed in Captain American: The Winter Soldier.
On Agents of S.H.I.E.L.D. Season 1 Episode 17, Coulson accuses May of working against them. She proves her loyalty despite her betrayal. It's unclear who should be trusted as Victoria Hand and Coulson each believe the other is working for the enemy.
The truth is shocking and will change the show forever. You'll want to watch Agents of S.H.I.E.L.D. online right away to prevent being spoiled.