
The series stars Clark Gregg as Phil Coulson, reprising his role from the film series, alongside Ming-Na Wen, Brett Dalton, Chloe Bennet, Iain De Caestecker, and Elizabeth Henstridge. Nick Blood, Adrianne Palicki, Henry Simmons, Luke Mitchell, John Hannah, Natalia Cordova-Buckley, and Jeff Ward joined in later seasons. The S.H.I.E.L.D. agents deal with various unusual cases and enemies, including Hydra, Inhumans, Life Model Decoys, alien species such as the Kree and Chronicoms, and time travel. Several episodes directly cross over with MCU films or other television series, notably Captain America: The Winter Soldier (2014), which significantly affected the series in its first season, and Agent Carter (2015–16), from which series regular Enver Gjokaj joined the cast for the seventh season. In addition to Gregg, other actors from throughout the MCU also appear in guest roles.
Premise
The first season follows S.H.I.E.L.D. agent Phil Coulson as he puts together a small team of agents to handle strange new cases. They investigate Project Centipede and its leader, "The Clairvoyant", eventually uncovering that the organization is backed by the terrorist group Hydra, which has infiltrated S.H.I.E.L.D. In the second season, following the destruction of S.H.I.E.L.D. in Captain America: The Winter Soldier (2014), Coulson becomes director of the organization and is tasked with rebuilding it while dealing with Hydra, a faction of anti-superhuman S.H.I.E.L.D. agents, and a newly-revealed superhuman race called the Inhumans.
In the third season, Coulson begins a secret mission to assemble the Secret Warriors, a team of Inhumans, as Hydra restores its ancient Inhuman leader Hive to power. After the defeat of Hive and Hydra, S.H.I.E.L.D. is made a legitimate organization once again with the signing of the Sokovia Accords. In the fourth season, Coulson returns to being a field agent so S.H.I.E.L.D. can have a public leader, and is tasked with tracking down more enhanced people, including Robbie Reyes / Ghost Rider. In addition, Agent Leo Fitz and Holden Radcliffe complete their work on the Life Model Decoy and Framework virtual reality projects.