http://german.stackexchange.com/questions/31211/mit-nach-hause-nehmen-grammatikalische-analyse explains it far better than I ever could. Basically it seems as if it is the verb "mitnehmen", but according to these guys it's NOT. "mit nach Hause" is apparently a prepositional construct and "nehmen" is the verb. But I assure you, as a native speaker, I would have totally thought it's mitnehmen and some crazy ass exception rule. Who knew.

[...] wer die Beste ist und wer eine Urkunde mit nach Hause nimmt. [...] wer die Beste ist und wer eine Urkunde nach Hause mitnimmt. Both sound fine to me.