plot idea:
a wheelchair-bound GrandParent and their adult GrandChild are hunted by an Assassin in a big city where they don't speak the first language. plot goes from morning to evening on the same day? grandparent can be a badass, in which case thriller. otherwise horror.
A is overweight, letting them hide a disassembled sniper rifle on their body, but preventing them from relocating quickly or trying to kill them up-close or sneak up on them. A has a grudge against the GP, and wants to kill them personally. A is very rich. rifle is fancy and has fancy ammunition.
start: GC wakes up and checks phone, to find it's out of power despite being plugged in. it's cold. GC alerts GP power's out. GP was already awake and aware, and has covered themselves with a blanket, but was letting GC sleep. GC goes to check power. hears glass breaking something falling on the floor. runs back up to a broken window and GP who has either dropped on the floor and crawled to cover or tilted their wheelchair onto the back and rolled into cover.
protagonists try to get out of the city, or to get the police involved.
Twists:
protagonists try to pay for goods and services, but find out their cards have been reported stolen.
protagonists keep getting shot at from a specific direction, the direction of the sun. they get so good at avoiding it they're not shot at for a while, but then it turns out A has been relocating, and they're shot at from a different direction.
GC meets an ex by chance and gets help. said ex turns out to have been directed to them by A to lead them into danger. A has a source in CCTV for the city, and always knows where they are.
police are tied up, because there is a bomb threat against the police station and various other places, and there's actually been an explosion at an important light rail/subway location.
they almost get help from a stranger, but the stranger gets shot.
A hits GC's leg. they manage to both ride the wheelchair, but not upwards. GP has pain, not total paralysis in legs. GP pushes wheelchair upwards with great pain and difficulty. just when they reach the top of the slope, GP is shot through the chest. It turns out A has been missing because they were specifically aiming for GC's leg, they want GP to suffer as much as possible.