Catherine (played by American actress Peggy Trentini) was a femme fatale and arguably the film's antagonist. She is the the mistress of Dean Wallace, a wealthy business man. In Catherine has been having an affair with unknown to Dean's second wife, Lauren, and lives in a posh penthouse provided by her lover, spending his money and going on luxurious overseas trips to her benefit.
When she learns that she needs to move out due to the building being renovated for a few weeks, she stormed into Dean's office demanding him to fix it so that she would not be homeless. Catherine found that Dean was in a meeting with Mick Curtis a masseuse that she went to for massages and other additional "services", before hooking up with Dean. Though she eventually broke up with Mick as he was broke. Like herself, Mick was seeking a benefactor to give him a loan so that he could open his own massage spa. Unknown to Dean, Mick arranged the meeting with the businessman by seducing the man's daughter and wife, who were clients at the spa he worked at.
Upon learning that the two used to be an item, Dean had some doubts of investing in Mick's plan despite Catherine's reassures it was in the past. Though she still maintained her lover's interest in the investment, praising Mick as the best in his field. After Catherine left Dean, after be assure the penthouse would be taken care of, Mick approached her teasing her about being in Dean's pocket, though Catherine defended herself stating that she did him a favor, which Mick retorted that he did not need it since he had Lauren's support.
Catherine bitterly laughed at Mick, as he was still up to his old tricks of seducing women and sleeping as a means to boost business to keep women coming to him for his services. Mick still having some feelings for Catherine demanded to know why she stopped seeing him, which Catherine answered she preferred the company of Dean and his affection, which Mick attributed to her leeching off the man.
Before they parted ways, Catherine wished Mick luck on his spa stating she would see him if it opened. Mick worried that Catherine would ruin his chances of getting an investor them visited her penthouse, claiming he wanted to talk, though the two bedded up making love and seemingly rekindling their relationship.
Later after Catherine had a love-making session with Dean, she managed to convince him to invest in Mick's idea. She began to feel threatened when Dean wanted to spend more time with Bonnie as a father and tried to discourage him from forming a positive paternal relationship, arguing she was old enough.
Lauren though was on to the lovers and their affair, finding Catherin's bra, proof of Dean's infidelity in his office and keys to her penthouse. Disheartened but not surprised, Lauren went to Mick to be in his embrace, after telling him of her husband's unfaithfulness. After Lauren left, Catherine met with Mick who warned her that the wife was on to her affair and it was dangerous for them to meet. Catherine was not discouraged as she wanted to talk to Mick about their relationship.
The two went to her penthouse, where Catherine told Mick her plans of moving onto the next place if her affair with Dean went sour. When asked on choosing the option to settle down, Catherine declined as it was not for her and encouraged Mick to sleep with her.
The next day Dean learned of Mick being intimate with his daughter, after she claimed to have found love, at the same time Lauren found Catherine's penthouse using the spare keys. Dean angry at Mick for this, went to Mick's workplace, where he ran into a scene of Catherine and Mick having sex, revealing their illicit tryst. Lauren arrived to inform Dean she knew that her husband was cheating on her and threatened to sue him. Dean's anger was compounded when Catherine revealed that Mick was sleeping with Lauren and the latter's own infidelity. Things even got worse when Bonnie and Kate, Mick's roommate and current girlfriend, arrived with the former claiming that she loved Mick. Catherine though quickly informed the girl the ménage à trois situation, causing her to be devasted. That being it, Dean planned to discard Mick's loan and blacklist him from every investor in town.
Kate though brought up the night she and Dean slept together, citing he had no moral high ground either. Seeing that they were in a awkward situation. Dean relent and agreed to invest in the spa on the condition that they never speak of this entire incident, while Lauren agreed to stop sleeping with Mick, and become a more devoted wife and step-mother to Bonnie who decides to leave for college to get away and also connect with Lauren more. Mick seeing the consequences of his actions, swore to Kate never to sleep with other women again.
Catherine on her part tried to keep her penthouse but was rejected by all parties, with Kate standing up to the bimbo to run off and find another wealthy millionaire.