'Billions' Season 4 Adds Samantha Mathis (Exclusive)

Samantha Mathis - Getty - H 2018
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[This story contains spoilers for the season three finale of Billions.]

Taylor Mason Capital is getting some reinforcement in the fourth season of Showtime's Billions.

Samantha Mathis (The Strain) has joined the series for a season-long arc. She will play Sara Hammon, the new COO of Taylor Mason Capital, who is brought on board by Taylor (Asia Kate Dillon) to help run the newly formed company and protect it — and Taylor — from Axe's (Damian Lewis) aggression.

Taylor likely has good reason to be concerned, as the third-season finale saw the character leaving Axe Capital to start a new firm — with a few billion dollars in capital Axe thought was headed his way.

Mathis' film and TV credits include American Pastoral, Under the Dome, Law & Order: SVU, The Good Wife, Lost, Salem's Lot and How to Make an American Quilt, for which she earned a SAG Award nomination as part of the film's ensemble. She next will be seen in the movies Boarding School and The Clovehitch Killer, both of which are due for release later in the year.

Mathis is repped by Paradigm and MGMT Entertainment.

Season three of Billions averaged 5 million weekly viewers across platforms; it is Showtime's second most-watched drama behind Homeland. The fourth season is due in 2019.