I have created a mod idea:
SpecOps (May change name later)
The story is, your a spy working for Gordan Freeman. You pretend to be a Civil Protection and eventually Gordan is captured! Immediately when you told the other Civil Protection agents not to kill him, they discovered your identity. So you run through perilous levels to save him before he is executed. At the end, you sacrifice your life for Gordan.
The name of the character is unknown and he does not talk.