The Last Day is the eighth episode of the fifth season of the television series Agents of S.H.I.E.L.D., and the ninety-sixth episode overall.
Coulson and the team discover that the most unexpected person from S.H.I.E.L.D.'s past may hold the key to preventing Earth's destruction.
After crashing the Trawler on the surface of the Earth, Phil Coulson, Daisy Johnson, Leo Fitz, Jemma Simmons and Deke Shaw are rescued by the True Believers, who take them to the remnants of the Zephyr One which have survived the cataclysm of the destruction of the Earth. They are greeted by Samuel Voss, Deke's friend, who tells Deke that his father Owen Shaw is on his way back to the Zephyr One.
The S.H.I.E.L.D. team unsucessfully tries to get answers from Robin Hinton, who is still lost between times and can only tell them ominous enigmas. Flashbacks show that following the death of her mother, Robin was taken to the Lighthouse and was raised by May. Other S.H.I.E.L.D. agents were also present at the Lighthouse: Fitz and Simmons unsuccessfully worked on a way to prevent the global disaster and Yo-Yo Rodriguez rebelled against the Kree when they sought to take control of the Lighthouse.
Johnson and Deke have a conversation about their respective fathers and Johnson tells Deke that he should not worry about his impending reunion with Owen. Fitz and Simmons discover a strange mechanism in the Zephyr One and Voss explains that it was built by Owen to bring the S.H.I.E.L.D. agents from the past. Later, Coulson and May discover that the True Believers have a fragment of the White Monolith which fits into the mechanism discovered by Fitz and Simmons. However, Deke is visibly troubled by the fragment. He confronts Voss about it, claiming that it belonged to his father and that Owen would never have left it far from him. In response, Voss punches Deke and locks him away, and Deke figures out that his father had already been killed by Voss.
Fitz and Simmons discover that they are locked in the mechanism's room as well. As Johnson is still trying to get answers from Robin, she is approached by Voss, who tells her that there might be a way to prevent the Earth destruction: keeping Quake from returning to the past so that she cannot trigger a massive earthquake. Thus, the True Believers attack the S.H.I.E.L.D. agents. Although the S.H.I.E.L.D. team eventually defeats their opponents, Robin is stabbed by Voss during the fight. In her last moments, Robin is comforted by May. She reveals that May took care of Robin and raised her, much to May's astonishment. Before dying, Robin informs May that Flint, the Inhuman who is known to everyone in the S.H.I.E.L.D. team except May, is the key to their success in saving everyone.
In the Lighthouse, Kasius sends Sinara to chase the fugitives on Earth and decides to punish the inhabitants by cutting down the power and releasing Vrellnexians from the sealed levels where they are contained. The survivors blame Flint for this as it would not have happened if he had turned himself over to the Kree Watch, but Alphonso Mackenzie and Rodriguez defend him.
Together, they head to the level 3, where they reclaim the crate of weapons hidden by Fitz decades ago, including the Shotgun-Axe and some Splinter Bombs. Fully armed, they manage to exterminate the Vrellnexians, growing gratitude among the remaining Lighthouse's inhabitants, who ultimately decide to join them in their fight against the Kree. Meanwhile, Sinara finds the remnants of the Trawler and Kasius orders her to track down the fugitives and to bring Quake back alive.