"Lara's Theme" is a leitmotif, or a constantly recurring musical phrase, that was created by composer Maurice Jarre in 1965 for the film "Doctor Zhivago". The movie features a traditional Russian instrument called a balalaika, which sounds very similar to a mandolin.
After the movie's release, this song became an international success, and lyrics were eventually added at the request of singer Connie Francis. While her version didn't even make the charts in the US, it became her biggest success internationally - even reaching Number 1 in Italy. The Ray Coniff Singers produced the most successful version in the US, reaching Number 9 on the charts.
If you are trying the melody part, please note that you will have to go in to third position in order to reach the higher notes. It might help to review your Third Position Exercises before trying the song.