In Hitman 3's final mission location, the Carpathian Mountains, Agent 47 must fight his way through a train filled with Providence agents in order to take out The Constant, Arthur Edwards. This mission is the official conclusion to the World of Assassination Trilogy.
To see the normal ending, simply eliminate Edwards using any weapon. He even handily provides Agent 47 with a vial of serum which the agent can then turn around and use on Edwards to end his life.
However, this final mission also features a hidden secret ending, which some players may miss on their first time through. The secret ending sees Agent 47 questioning whether or not he can trust his handler, Diana Burnwood, and whether eliminating the Providence organization is truly the right thing to do.
Here's how to unlock Hitman 3's secret ending and see an alternate conclusion to 47's journey:
How to get the Hitman 3 Secret Ending
Once you reach Arthur Edwards' car, he will begin talking to Agent 47 and will eventually point out a hypodermic needle filled with serum on his desk. Remove the serum from its case and equip it, but do not use it. Trying to attack or kill Edwards could potentially lock you out of the path to the secret ending, so avoid that.
With the serum equipped, stand there doing nothing and listen to Edwards talk. Hold on to the serum for about a minute without taking any other actions. After the minute has passed, Edwards will suggest that 47 inject himself with the serum and wipe his memories. A prompt will appear asking 47 to inject himself with the serum. Do as the prompt says to unlock the secret ending cutscene.
Viewing the secret ending will complete the challenge "A New Father" and unlock the achievement "Count Down from 47."
Make sure to check out TechRaptor's other guides for tips and tricks on how to complete some of the other challenges and missions in Hitman 3.