In the narrative, the inspector performs an insurance assessment aboard the East India Company vessel Obra Dinn, which unexpectedly arrived to Falmouth, England with no crew onboard in 1807 after having been missing for several years.
A boatman takes the inspector aboard the Obra Dinn in 1807. They bring a box that contains a catalogue and a pocketwatch, both mailed to the East India Company by Henry Evans, a surgeon aboard the vessel when it went missing.
Using the pocketwatch on bodies and remains found on the ship, the inspector deduces what happened aboard the ship during its final voyage in 1802. This inspection forms the bulk of the game with different death sequences presented as flashbacks.
When the inspection is done, it starts to rain and the boatman asks the inspector to return so they can get back to shore before the storm hits. After the two leave, the Obra Dinn sinks in the storm. A week later, the inspector mails the catalogue back to Henry Evans in Morocco and concludes the insurance investigation for the East India Company.
The narrative then jumps one year ahead, and the inspector is at home. They receive a letter about Mr. Evans' death. If the inspector deduced the fates of all hands aboard the Obra Dinn correctly, they also receive a package that gives a chance to use the pocketwatch to find out about events in the lazarette of the Obra Dinn, which was inaccessible a year earlier. When done, the inspector places the catalogue to their bookshelf and the game ends.
The game uses internal focalization and first-person point of view so only the hands of the inspector are seen in the game. The inspector wears gloves in all instances where their hands are seen.
Their name is never fully revealed in the game. The signature is almost illegible except A, the initial of their forename.
The game chooses between two voice options (voiced by Adam Beauchesnesp or Debbie McCreadie) for the inspector when starting a new game.
The inspector has a maid who is not seen but opens the front door and accepts the delivery containing the letter (and possibly the catalogue) in the epilogue.
- Stated in a letter when starting a new game.
- The final insurance assessment book mentions that the ship sank in Falmouth.