What will you do if you found out that a friend is secretly planning suicide

Lots of people are fed up with life. If you check the number of people are committing suicide everyday, you will be shocked that quite a large number of people are intent on taking their own lives. The pain and grief that follows suicide are usually unbearable. Surviving family members and friends only wished they could have done something to help. Now lets give you a second chance. You discovered that your friend is planning to take their life. He or she is completely unaware that you have found out what they are planning. How will you handle it?