During her birthday party, Katie is showing signs that her health may be deteriorating. Katie’s doctor arrives and tells Bridget that test results show that Katie’s body is rejecting the transplanted heart. Tensions rise between Ridge and Brooke, once again, when the subject of Donna comes up. When Eric arrives home and finds Marcus there, Donna continues the charade of Marcus being a caterer. Because of Donna’s suspicious behavior, Eric first assumes that Donna is pregnant. Eric then suspects that Donna may be having an affair with Marcus. Wanting to ease Eric’s mind of his assumptions, Donna blurts out that Marcus is her son.