The internet went dark-and the world didn't end. Not immediately. In the quiet aftermath, Eli Hart is just an engineer with solder-burned thumbs, a stubborn streak, and a stupid bet he made to impress a girl. Then the "heartbeat" begins. As Eli rebuilds a scrappy neighborhood mesh to help Mara-a fierce clinic doctor keeping people alive on paper and exhaustion-he uncovers a hidden Continuity program counting down toward Day 100, when "provisional access" ends and unverified people don't just lose the internet-they lose the right to exist. While the city lines up beneath glossy SafeNet banners promising stability, Eli, Mara, and his best friend Quinn race to build a quiet lifeboat: a minimum network of trust-medicine, identity, and survival-outside the system's control. But the closer Eli gets to the truth, the more the system seems to watch... and respond. A tense, emotional countdown told in day-stamped entries, Day 100 is a dystopian love story about secrecy, control, and the terrifying cost of saving people who can never know you did.