In the Dec. 19 episode of "The Bold and the Beautiful," Liam is over the moon because of Steffy's pregnancy. But for his father Bill, there is only one question: Is he the grandfather or the father of Steffy's baby?

The previous episode saw Steffy (Jacqueline MacInnes Wood) and Liam (Scott Clifton) accidentally finding out that she was pregnant in a routine check-up. The couple has almost given up on having a baby together after Steffy's previous miscarriage, and the news is nothing short of a miracle.

Liam was practically jumping with joy. But for Steffy, who is not sure who is the father, the world came crashing down.

In the Tuesday episode, Liam will not waste time telling the important people in his life about the great news. First up is his younger brother Wyatt (Darin Brooks), who will share in his happiness.

Steffy beats him into telling his dad Bill (Don Diamont), though. After all, they have a lot to discuss.

They both swore never to talk about that one night of passion in the guesthouse. While Bill has insisted they are in love, he has so far respected Steffy's decision to stay with Liam. But for how long?

Bill will insist on a paternity test to find out who the real father is, as a dark fantasy hits Steffy, forcing her to decide her next move as soon as possible. She knows she has to tell her husband the truth one way or another, and the truth may ruin a lot of lives.

Meantime, things are heating up between Wyatt and Katie (Heather Tom). Brooke (Katherine Kelly Lang) is concerned that Bill would not like the idea of them dating, but admits that Wyatt is a good man for her friend.

Follow their intricate lives on CBS as "The Bold and the Beautiful" airs weekdays at 1:30 p.m. EDT.