Day 1
As seen in A Quiet Place: Day One and teased in the opening sequence of A Quiet Place II, the aliens crashed into Earth and quickly decimated the human population. Dubbed "Death Angels" in-universe, countless lives are lost in the initial invasion. Efforts by the military fail to turn the tide.
The military even isolates the survivors by destroying the bridges of Manhattan, hoping to contain the aliens. Despite the dangerous nature of the aliens, some humans (such as the Abbott family in upstate New York, as well as Sam and Henri in downtown New York City) are able to survive the initial slaughter. They also figure out how the blind Death Angels track prey through sound.
Day 2
Afflicted with cancer, Sam decides she doesn't want to wait to be killed, especially after her hospice nurse Reuban dies turning off an emergency generator that attracted Death Angels. Sam instead ventures out into the city to enjoy one of the "last" slices of pizza alongside her cat Frodo. Meanwhile, Henri and his family move towards a planned evacuation via local ferries. The Death Angels attack the crowds trying to reach the ferries, with Sam barely escaping. Frodo comes across another survivor, Eric, who Sam reluctantly allows to accompany her back to her apartment to sleep.
Sam and Eric move through New York City, doing their best to avoid the Death Angels. A number of close calls end with the pair (along with Frodo) being forced to move through the flooded New York subway. Reaching a church that's become a makeshift sanctuary from the Death Angels, the pair rest. Sam is hindered by her illness, forcing Eric and Frodo to head out into the night to locate medicine. Although he has a very close brush with the Death Angels, Eric successfully returns with the medicine and Sam recovers enough to move.
Day 3
Sam and Eric make their way to the pizza place, which is revealed to have been burnt down. However, the pair find another notable location from Sam's past (the jazz bar her father once placed at), and enjoy their time together. Sam ultimately convinces Eric to try and reach the ferries before they depart. Sam stays behind, creating a distraction so that Eric and Frodo can reach the same boat carrying Henri and his family to safety. Sam walks through the city and allows herself to be taken by a Death Angel in the ending of A Quiet Place: Day One.
The Abbott family — Evelyn, Lee, their daughter Regan, and their sons Marcus and Beau — survive the initial chaos by adjusting to new lives on a farm in upstate New York. The opening scene of A Quiet Place sees them venturing into a nearby town for supplies. While there, Beau ends up enamored with a toy rocket.
Day 89
Despite the warnings of his father and the efforts of his sister, Beau makes too much noise with the toy. This ends up attracting the attention of a Death Angel. The creature quickly kills Beau, forcing the Abbott family to move on without him.
Over the next year, the Abbott family are revealed to have fully adjusted to their new circumstances. The farm has proven a successful haven for the family, who have tried to move on after the death of Beau. Evelyn is also pregnant, forcing the family to prepare for the inevitable challenges of having a crying infant in an environment where any sounds can be a death sentence. The Death Angels are still a very present danger, killing some of the other few remaining neighbors the Abbotts have left.
Day 472
Much of A Quiet Place takes place during Day 473 and 474. While Lee takes Marcus on a fishing trip and Regan visits Beau's grave, Evelyn unexpectedly goes into labor early. In her pain, she makes a minor noise which attracts the nearby Death Angels. Her warnings successfully draw the attention of the rest of the family, however, who rush to try and assist her. Evelyn successfully gives birth to an unnamed child, and barely evades the Death Angels.
While Evelyn struggles to remain hidden from the Death Angels, her family attempts to make their way back to their home. Along the way, Death Angels also track Lee, Marcus, and Regan. Wounded during the efforts to reach Evelyn, Lee sacrifices himself so Regan and Marcus can make it back to their mother. Having discovered the feedback from her hearing aid can hurt the Death Angels, Regan is able to discover a weakness the humans can exploit. This allows Evelyn to kill the ones that are attacking them in A Quiet Place's ending.
Day 473
Much of A Quiet Place II takes place in the direct aftermath of the first film. With the farm house damaged beyond repair, the Abbotts head out on foot to find other survivors. Their journey leaves Marcus injured, but they are able to find their old friend Emmett in a steel mill he's refashioned into a home.
Regan heads out to find other survivors. Emmett reluctantly joins her, saving her from raiders and helping procure a boat. Meanwhile, Evelyn ventures out on her own to get medical supplies, while Marcus and his infant sibling become trapped in the mill.
Day 474
At the steel mill, Evelyn returns in time to save Marcus and her baby. However, they are cornered by a Death Angel. Regan and Emmett reach an island sanctuary, free of the Death Angels. There, they meet Henri. When a Death Angel successfully follows them and attacks the island, Henri helps the pair find a local radio tower. Although Henri is killed, Regan is able to use the radio tower to amplify her hearing aid. The sound proves debilitating to the Death Angels, even through a radio broadcast.
Hearing it over Emmett's radio at the mill, Marcus is able to stop and kill the Death Angel attacking them. At the same time, Regan kills the Death Angel at the island sanctuary, saving Emmett. This is the ending of A Quiet Place II, setting up a future where the humans know how to fight back against the alien creatures. This could set up all sorts of directions for future entries in The Quiet Place series.
