Total Recall

What is reality when you can't trust your memory? Arnold Schwartzenegger is an Earthbound construction worker who keeps having dreams about Mars. A trip to a false memory transplant service for an imaginary trip to Mars goes terribly wrong and another personality surfaces. When his old self returns, he finds groups of his friends and several strangers seem to have orders to kill him. He finds records his other self left him that tell him to get to Mars to join up with the underground. The reality of the situation is constantly in question. Who is he? Which personality is correct? Which version of reality is true?