The E3 demo takes place a few hours into the game during a period of unrest in a city ruled by a control freak called the Baron.
The population has had enough and decides to start a revolution, offering master thief Garrett the opportunity to infiltrate the Baron's manor and steal a precious gem called the Heart of the Lion.
The demo is played using a mixture of stealth and aggression, according to producer Stephane Roy, who's interviewed following the gameplay showing.
Set for release in 2014, Thief was recently confirmed for Xbox One in addition to the previously announced PS4 and PC versions.
In early April, we wrote in this Thief preview: "Garrett might well be most comfortable in the shadows, but in the run-up to next-gen Thief will have to deal with the spotlight. And on this first unveiling, at least, the stealth adventure isn't cracking under pressure."
For more on the upcoming game, check out our own Thief interview with producer Stephane Roy and lead level designer Daniel Windfeld Schmidt.