Perhaps the Grey Goo is created as a weapon by a new, shadowy organization in the Mass Effect universe. It gets out of control and starts to transform planets into a gooey mess. Shepard, or another main character, has to figure out who created it and how to stop it. They could discover that the key lies in some ancient Prothean technology that has the ability to neutralize the Grey Goo's self - replication mechanism.
One idea could be that the Grey Goo nanobots somehow get introduced into the Mass Effect universe and start to assimilate the technology there. For example, they might start with the Geth, who are already machines, and cause a new kind of conflict. The Reapers could also be affected, maybe the Grey Goo disrupts their harvesting cycle as it spreads uncontrollably.
A plot could involve a character from the Mass Effect series accidentally bringing Grey Goo to a new planet. This leads to the local ecosystem being destroyed as the Grey Goo consumes everything. The character then has to team up with unlikely allies, like a Cerberus agent who also realizes the danger, to stop the spread. They might try to find a way to reverse the Grey Goo's replication process using Mass Effect technology.
Look to Chapter 110 for the clearest answer. It begins with Jiang Li, carrying a wooden basin, walked over to the well., keeps building through Uncle Zhao's house didn't have a water heater, so she could only make do..., and lands on My parents died, and fortunately, Daddy found and took me in..
Chapter 116 is the strongest chapter-level answer because it starts from But before the audience in the live room had time to continue brewing the... and follows through on Their old Jiang family never had such twisted genes in hundreds of years!.
Chapter 133 is the strongest chapter-level answer because it starts from Watching Jiang Li and the others finish their meal and tidy up the table,... and follows through on It was only after she shared the concept and purpose of the show with him....
Chapter 128 is the strongest chapter-level answer because it starts from Still hungover, Huo Ziyang had just awakened from a blurry dream when his... and follows through on There had been no shortage of Weibo posts criticizing Jiang Li before..
If you want the clearest chapter reference, go to Chapter 80. Early on, Jiang Yan and Wen Jiaojiao, one so smug he was almost ascending to the...; later, the chapter leans on And this was exactly the scene Director Sun wanted to see..
If you want the clearest chapter reference, go to Chapter 111. Early on, The main room's door was pushed open just a crack, and the head of the...; later, the chapter leans on Miss Jiang, you're still up, that's great..
If you want the clearest chapter reference, go to Chapter 112. Early on, These five people are supposed to be at odds.; later, the chapter leans on When did they become so in sync?] [I'm dying of laughter hahaha why is....
If you want the clearest chapter reference, go to Chapter 137. Early on, Jiang Li personally went to Lai Fu's tomb and performed a small ritual.; later, the chapter leans on After it was finished, she took out talisman paper and gently waved it....
The best chapter pointer here is Chapter 165, "Boom! Jiang Yan is actually Su Yinwan's fanboy?!". It opens with How come everyone else got a solid six points, and he ended up with just... and closes on Various explosive Weibos sprang up like mushrooms after the rain, and....
Look to Chapter 122 for the clearest answer. It begins with Damn, are we supposed to find the points card in the mud?!" He had just..., keeps building through To salvage his image, he had deliberately dressed up before leaving the..., and lands on He had just steadied himself when Qi Tianyu.