Eventually, Freddie was arrested and thrown into prison with many thinking Tommy was the one who sold him out. Tommy ended up engineering a breakout during a prison transfer, allowing Freddie to escape. While it looked like Freddie was safe, at the start of season two it was confirmed he had died of the “pestilence”.

Did Tommy turn Freddie in?

Grace tells Inspector Campbell of Freddie's location, and the police come and take Freddie away. Ada, and the rest of the Shelbys believe that it was Thomas who turned Freddie over to the police, and as a result, Polly yells at Thomas, calling him a liar.

What did Freddie Thorne die of?

Freddie died of "pestilence"—likely the Spanish Influenza pandemic of 1918–1920—before the series begins.