secretly plan or cooperate with somebody
connive - scheme
When you ‘connive’, you scheme or do something to gain an advantage at the expense of others. It may not always be something illegal, but it is always dishonest or immoral. The term tends to be most commonly used in reference to shady business practices or criminal activity.
I did not connive with fiona to undermine you. We were simply trying to show our resourcefulness and initiative.
The police suspect that there was a connivance between a customs official and a businessman to smuggle the illegal goods into the country.
Jack is always involved in one shady deal or another. He’s a conniving so-and-so.