A very riveting introduction, I must say, and hard to pull off although you certainly did it with ease. Reminds me a little of the Bourne series, where the protagonist has a dark past that is slowly catching up to them.
The end certainly sets a definite tone. It hints that with the death of the sister, Alex will be forced to go on the run. No doubt there will be a lot of action soon to come!

Looking forward to the next chapter!