The phrase "vast conspiracy" refers to a secret and large-scale plan that involves a group of people working together for a malicious or harmful purpose. Full definition
Secondly, what vast conspiracy are you talking about? (sbnation.com)
In battleground states in the middle of the country, some Democrats watched with frustration as their party grabbed headlines last week with a splashy new lawsuit alleging a vast conspiracy between President Donald Trump and Russia. (morningconsult.com)
You'd be the first in over 150 years to do so and would completely dismantle the vast conspiracy of scientists that seek to replace God with atheistic naturalism and thus condemn the human race to fiery perdition. (religion.blogs.cnn.com)