In this page you can find the walkthrough for the prolog of Get Even which is a part of a memory called "The Kidnapping" (when you make enough progress in the game you can play the memories again, e.g. to make a different decision or find secrets that you have missed). During this stage you learn the basic mechanics of the game and you are able to investigate the first tracks.
Leave the building and start your linear walk through the forest. You notice a drone flying away and a guard going left. Left him alone (you can also shoot him - you are equipped with a pistol) and head to the entrance of the destroyed school. From this place onward you should start searching for tracks. The first one is the drone that can be scanned (use the right application from phone's menu and have the drone in the frame).
Move forward and use the stairs. The next track that can be scanned is a scrap of cloth that hangs on a heater.
You can also find an ashtray and a rope lying on the ground, both items are nearby. Scan both of them. Continue moving forward and in one of the next rooms you must find a bottle of nitrazepam. Once again you must use the scanner.
When you reach the staircase you must go down to the lower level. There is a guard around the corner, you can "test" executions on him. Crouch, sneak so you can be closer to him and use the attack button. After performing an execution you must reach the end of the corridor and scan the poster, the one at which the recently killed guard was shooting.
Continue your walk through the building. When you get closer to a new enemy the game will allow you to test the CornerGun that allows you to shoot enemies around the corner. Its two main advantages are a lower chance to be detected and a much higher level of safety thanks to being able to shoot without peeking from a cover. Use this weapon from the corner on the right. Next, by using thermal vision you must locate a new enemy and kill him with a headshot.
The last part of this memory takes place in the room where Grace is imprisoned. Use the slow motion to kill the two guards without any problems.
Sadly, Grace can't be saved even if you decide to interact with the bomb and use the code that she gives you - 3001. Soon, the prologue ends and you can move to the next stage.