Answer the phone.

Rachel has a blackout, waking to find herself smothering her boyfriend, Jack to death. By the time she realizes what she has done it is too late. Rachel flees the scene of the crime, ending up at a hotel on the other side of Chicago. Once she has gotten settled, the phone rings. The caller claims to be a witness to the crime. This witness has been watching Rachel for a long time and doesn't plan to let her off easy.