What has the Lambert family been up to since we last saw them in Insidious: Chapter 2?

When last we met the Lambert family, astral projectors Josh (Patrick Wilson) and Dalton (Ty Simpkins) had survived multiple trips into The Further. Dalton had been kidnapped by a demon… Josh had rescued him, only to be trapped in The Further while a ghost possesses his body in our world… that ghost, in Josh’s body, had rampaged through his house, trying to kill his family… and Dalton had ventured back into The Further to find his real father and bring him back.