Adrien Brody sees dead people — so, so many dead people — in Backtrack, an Australian hybrid of The Sixth Sense and every thriller to ever feature “retrograde amnesia” as a laughable plot device. In Michael Petroni’s nonsensical mystery, Brody is Peter Bower, a therapist who’s still grieving over the traffic-accident death of his daughter, and who comes to realize that every one of his patients (including Sam Neill’s psychologist, and a spooky, screamy young girl) is dead, and in fact died on the very same date in 1987.

That’s also the day that Peter, as a kid, was involved in a train accident that killed scores of innocents — a connection that motivates Peter to go back home, visit his drunken ex-cop fa...