September in Boston smelled like salt air and possibility.

Lily Kane stood in the locker room of the brand-new Fleet arena, her crimson pro jersey hanging in front of her with “KANE 18” stitched across the shoulders. The fabric felt different—heavier, real in a way college jerseys never had. Around her, teammates chattered in a mix of nerves and excitement: veterans from the inaugural PWHL season, rookies like her, and a few international stars who’d joined for the league’s ...