Searching for an explanation

Saw this film on you tube yesterday.

I liked the twist .. for most of the film , I thought Jack was the serial killer instead he turned out to be a mercenary on the run and all the close neighbours he engaged with were all alive.

Can someone explain to me why Adrian decided not to leave for California anymore with Jack ..what was Adrian looking for in the suitcase on the couch .. the gun to kill Jack or just to hold him hostage?