Re-started this late on Sunday, the first in the Dan Forrester series.
From the Blurb:
Dan Forrester, piecing his life back together after the tragic death of his son, is approached in a supermarket by a woman who tells him everything he remembers about his life - and his son - is a lie.
Grace Reavey, stricken by grief, is accosted at her mother's funeral. The threat is simple: pay the staggering sum her mother allegedly owed, or lose everything.