Yesterday and today and tomorrow

Three friends live in a safe mind and always are happy when she is with them during her day .. One night when she slept, the three friends differed on the most important of them in her life! They agreed that one of them was absent from working in a safe mind one day, and the effect of this absence appears .. See, how will the game end? What will they discover at the end? This is what you will know when you read the story of "Yesterday ... and today ... and tomorrow" ..