A young man disappears in the wilderness of the California mother lode. He leaves behind a gold-flecked rock and a vial of liquid mercury. He is a misfit in the modern world, a throwback to the Gold Rush days.A venture capitalist — whose gold country is Silicon Valley — hires forensic geologists Cassie Oldfield and Walter Shaws to track his missing brother.Following one of the 'lost rivers' of California, Cassie and Walter plunge into the dark history of the legendary lands, into the dark past of the brothers, into a poisonous sibling feud that threatens both lives and the land.And the question then becomes: which brother is on the hunt?