She went from being a half-hearted model to starring on the critically acclaimed Starz romance series Outlander.

Yet Caitriona Balfe wasn't even attached to the series with only days to go before production started on the first season.

The series' showrunner Ronald D. Moore revealed Wednesday in an interview with Collider that the 40-year-old actress had to immediately hop on a plane for Scotland after winning the role. 

Last minute: Outlander showrunner Ronald D. Moore revealed to Collider Wednesday that series star Caitriona Balfe was only cast a days before shooting began on the series; shown in February

While speaking via video chat with Collider Editor-in-Chief Steve Weintraub, Moore said he initially expected Caitriona's role as Claire would be the easiest to cast.

Instead, he immediately knew Sam Heughan was right for her lover, but had trouble nailing down her part. 

'In the beginning, I said, "We're going to cast Claire first because she'll be the easiest to find because she a smart 20th century British woman, and there're lots of them,"' Moore said.

It was Jaime, the role that Heughan filled, that Moore anticipated being difficult to cast, but instead he was the first person cast for the series.

Reversal: While speaking via video chat with Collider Editor-in-Chief Steve Weintraub, Moore said he expected Balfe's role to be easiest to cast, but Sam Heughan was the first person cast