Basically my story is a thriller where in third act, the MC's revenge plan is to frame the villains, and manipulate the police into going after them, for him. Sort of like the classic playing one side against the other plans. However, the police who becomes part of his plan to manipulate them, don't really have a role to play hardly, before the third act. They are not really part of the story, and don't really have much to do, before then, since it's the MC doing things by himself. In fact it is essential that the police do not have a role to play prior, because if they did, they would have known too much, and therefore, wouldn't have been able to be manipulated into such a plan, cause they would already know what is really going on, if they had been part of the plot prior. So I was wondering, how can I introduce a group of police that are part of the MC's plan in the beginning of the third act, without it coming off as out of nowhere, or a possible deux ex machina if you will, since their is not much for them to do in the story prior, plotwise?