Julia Schlaepfer had just one day to tear her 1923 character down to the studs and rebuild her stronger than ever.

The road trip from hell has only just begun for Alex. In the latest episode of the Yellowstone origin series, Spencer’s wife (played by Julia Schlaepfer) disembarks her ship after a precarious ocean voyage, only to encounter more horrors while passing through Ellis Island.

The actress, 30, tells PEOPLE how filming the "really brutal" sequence went — and reveals how challenging she found it to separate Alex's story from hers

Schlaepfer's character is sexually assaulted when she reaches Ellis Island, in hopes of reuniting with her American husband (played by Brandon Sklenar): "No one should have to go through what she goes through.