conspire with

conspire with someone (against someone or something)

 and conspire (with someone) against someone or something
to join with someone in a plot against someone or something else. The CEO conspired with the board of directors against the stockholders. Ed conspired with Sam against the plan.
See also: conspire
References in classic literature ?
I wrapp'd myself in grandeur then, And donn'd a visionary crown -- Yet it was not that Fantasy Had thrown her mantle over me - But that, among the rabble - men, Lion ambition is chain'd down - And crouches to a keeper's hand - Not so in deserts where the grand The wild - the terrible conspire With their own breath to fan his fire.
I guess we'll never let you go, Matt," he whispered, as though even the dead, lovers once, must conspire with him to keep her; and brushing by the graves, he thought: "We'll always go on living here together, and some day she'll lie there beside me.
His solicitor Cornelius McCarthy told the court: "He denies totally that he conspired with anyone and says there is no evidence that he did conspire with anyone.
The victim, an Armenian immigrant who came to the United States last year seeking political asylum, was reportedly forced to conspire with the five in a scheme to cash false checks for an unknown amount of money.