Good read for those who wants to understand the story.
In a near future America president Bridgett Strand is hospitalized and is left comatose. In the coma her Ka(soul) and her Ha(body) are separated but both live on as separate beings. Her ka arriving into the beach (another dimension where the dead go but not the afterlife) she learns about her being an EE (an extinction entity). There have been 5 EEs before her which are now called The Big Five. These entities were responsible for events such as the big bang and the extinction of dinosaurs and etc. And she was to be the last so to say bang. At the same time her ha waking up in the world decides to create a facade for her ka and names her Samantha (Amelie) America Strand her daughter. Also Amelie doesn't age while Bridget does.
Working together they try unearthing the knowledge of past generations through the beach. But to achieve this they devise a thing called a chiral network that they hope will connect humanity. As a basis for the network they attempt to use a prototype BB (bridge baby) a being serving as a bridge between the world of the living and the dead which we later discover is Sam Bridges the protagonist of the game. BB is the son of Clifford Unger (an ex military captain) and Lisa Bridges (who is in a coma and serving as a stillmother to BB).
Upon hearing about BBs transfer to another facility John (an ex soldier in Cliffs unit and later known as Die-Hardman) offers his captain a chance to escape saying that he will never see BB again if hes transferred. He accepts reluctantly kills Lisa and attempts to escape with BB. He fails and is killed. But a bullet also kills BB. This prompts Amelie to use her EE powers to resurrect BB making him a repatriate. This anomaly seemingly shifts the balance between our world and the beach (matter and antimatter) and results in an event known as the Death Stranding. This event brings the dead back as BTs (beached things) makes a gold-like substance called chiralium appear and as chiralium disperses in the atmosphere creates chiral clouds and subsequently produces timefall (a type of rain that if touched with a surface be it organic or non-organic speeds up the aging process). Bridget decides to raise baby Sam as her own.
Decades later the now grown up Sam marries a woman and this woman becomes pregnant. In an unknown accident she is killed and her body goes into necrosis (a state where if touched by a BT the reaction between matter and antimatter causes a nuclear level explosion) and is blown up. This prompts Sam to leave Bridges (an organization tasked with connecting the world using the chiral network) and work as a Porter (an independent delivery man). Sam also discovers he has an affliction called DOOMS which based on the level allows the person to sense, see and even control BTs. Sam can only sense them.
During a delivery Sam is caught in a timefall and seeks shelter. He is then confronted by Fragile of Fragile Express (a private delivery company) and upon her touching his arm a visible allergic reaction appears. Sam has Aphenphosmphobia an extreme fear of intimacy. That includes physical touch, which is why Sam reels from hugs or even simple handshakes in the game. But it is also a fear of "emotional bonds,". Sam after making the delivery is confronted by Deadman and is encouraged to have a conversation with the now dying Bridget. On his way he chances upon Igor a man from the Corpse Disposal unit who requires help with burning a body. Curiously Igor has a BB (namely BB-28) strapped to his chest which he uses to sense BTs and avoid BT territory. On their way to the incinerator theyre caught in a timefall storm and the body they were carrying enters necrosis. BTs find their way to the body and it explodes leaving a crater in its wake. Because he is a repatriate Sam comes back to life and takes the BB-28 with him.
After a conversation with Bridget she tasks Sam with finishing her work reconnecting America by adding Knot Cities to the chiral network. He is explained by Die-Hardman that Amelie together with Bridges 1 was sent from Capital Knot City to the other coast reconnecting people on the way. But before reaching Edge Knot City bridges was ambushed by a terrorist organization called the Homo Demens lead by Higgs (the guy in the golden mask) and everyone but Amelie was killed. Sam later sees Amelie in a dream in which she says to Come and find her on the beach. Sam reluctantly agrees to help bridges reconnect America. He is given cuff-links a device that look like hand cuffs which help him navigate and stay connected to the network
The next part of the game involves Sam going from knot to knot making deliveries and reconnecting them to the chiral network. He is confronted by Higgs multiple times where we learn that he possesses the ability to control BTs. We also slowly learn about the stories of supporting characters like Heartman whose heart stops every 21 minutes, and after dying, for three minutes he searches for his family on the other side, before being resurrected by the automated external defibrillator (AED) on his chest. Deadman whose body is 70% Harvested from cadavers also being grown from pluripotent stem cells redeeming him motherless, he calls himself "Frankenstein's monster". Mama who in the wake of a terrorist attack was crushed under the rubble of her lab and inadvertently survived by "giving birth on the other side", resulting in the baby manifesting as a harmless beached thing. Stuck for days drinking timefall, Mama was eventually rescued by Bridges, but left her unable to leave the lab.
And Fragile the daughter of the founder of Fragile Express, when he died, the torch was passed down to her. She and her company eventually merged with Higgs Monaghan's delivery company, drawn to his vision of the future.
Early on, they were highly successful in delivering supplies to those in the most remote of areas, but all too quickly it was discovered that Higgs was a terrorist leading the Homo Demens. They had gone from delivering food and medicine for communities to smuggling guns and bombs for terrorist cells. Fragile was tricked into bringing a nuclear bomb into Middle Knot City, resulting in the deaths of everyone there. Fragile discovered that Higgs was delivering another nuke to South Knot City and managed to steal it away from them, only to be caught by the terrorists. Fragile was stripped down to her underwear and given a choice by Higgs: save the city by running through timefall (which he had summoned) and throwing the bomb into a tar pit, or warping out of the area and saving herself, at the cost of all those who lived there. Fragile chose to save those in the city, and Higgs gave her his mask so that her face would be protected, wanting for her face to be a testament to those who crossed him (and for it to be remembered as belonging to the person who nuked Middle Knot City). Because of this, the rest of Fragile's body deteriorated as the price for South Knot's continued survival.
Most importantly thought Sam learns the story of Cliff in forms of flashbacks when he is connecting with Lou (BB-28). He is also in three instances confronted by Cliff himself in his BT form. In the last encounter Cliff gives Sam his dog tags and with a bang of a gun disappears.
The next two hours of the game are a 2 hour long cutscene where Sam with Fragiles help enters Amelies beach and is told that once he goes in there's no coming back. There he learns of her being an EE and Amelie attempts to initiate the last big bang and is interrupted by Sam. Amelie explains that all he will do would be to delay the inevitable and that the extinction is an opportunity for mankind to adapt by surviving. Nevertheless the extinction is prevented and Sam is stuck on the beach where he is explained by Amelie why she did what she did.
Sam later starts hearing Deadman's voice which prompts him to enter the sea area of the beach where he is grabbed by Deadman who is using Lou to find Sam.
The next cutscene involves Die-Hardman being appointed as the new president. His very emotional talk with Sam telling him how he regrets what he did to Cliff and Sam is still angry with him. Deadman gives him the now decomissioned BB-28 Lou and explains that an order was given to take the pod to the incinerator and that if not performed it would be a seen as a great offence. But he also informs him that the area where the incinerator is disconnected from the chiral network so if he deactivates his cuff links there he would be untracable. He then hugs Sam who doesn't reel away from it seemingly overcoming his phobia.
Arriving at the incinerator sam connects with Lou for the last time and we see the events of Cliffs escape and Sam's death. Cliff hugs his son telling him that he is Sam Bridges his and mankind's bridge to the future.
Activating the incinerator he chooses to put the cuff links and opens Lou's pod knowing full well that there's only 70% chance of his survival. Luckily Lou takes his breath and is alive. We then see Sam clutching sam to his chest and the scene ends.
In an after credits scene we see Lou playing with Sam's hand and a picture of his wife and him is also seen.
Sam calls out the name Louise prompting me to believe that BB-28 is a little baby girl.