The witch of babylon

Samuel dies in a car accident, while his brother John lives through it with minor injuries. Six weeks later, family friend Hal dies from an overdose and John discovers that Hal stole from Samuel a valuable piece of art that Samuel saved from the National Museum in war struck Baghdad. A few days later, John, who decides to cooperate with the police, receives a post-mortem riddle from Hal. If he manages to solve it he will recover the lost art piece.