An episodic noir murder mystery, D4 features a dark story that contrasts starkly with the occasionally humorous characterisations found in the game and the colourful, cel-shaded art style that is somewhat reminiscent of Telltale's recent The Walking Dead series of adventure games.
The game stars David Young, the player-character and protagonist of D4. David's wife - Peggy Young - was recently murdered, and David, who is a private detective, takes it upon himself to investigate and solve the murder.
At some point after the events surrounding her death, and possibly as a result of the stress those events brought upon David, he loses his memory, but simultaneously acquires a limited ability to time travel.
David is unable to time travel at will to the time and place of his choosing, but is able to travel to points in time by refreshing his memory of those particular events. This is typically done by finding a key object that will trigger David's memory. Using this ability, the player must attempt to solve the mystery of his wife's death and potentially prevent her murder altogether.
