Flea went into psycho-cat mode and had another go at Finn. It was terrifying holding onto Finn's collar - holding him back - and trying to get the two to calm down. After about a minute Finn calmed down enough that he'd stay put long enough for me to walk over and grab Flea by the scruff of her neck and lock her in the bathroom.
Finn's locked in the laundry now. Flea's growling at him through the door. Her tail is still puffy and she's giving me "airplane ears".
It's far too quiet here now. :/