The story follows group of friends,each with different idealism and with love for wrong person,as they begin suspecting some of them actually killed their friend who died in an accident.

We need to know number of friends and an event. Think of the Big Chill. Based on that.

Four friends come together for a funeral only to start blaming each other for course their friends death.

Now describe the friends

1) war veterans
2) college friends

You get the picture.

Moses99 raises a very good point. What is the inciting incident that raises suspicion that the death wasn't just accidental?

I agree with dpg that the revision is a vast improvement but an inciting incident would elevate the logline to a new level. If it is believed to be an accident what is the point that triggers the characters to suspect that it is something more sinister? Add this at the head of the logline and you're all set.