Upasana's sickness

Saloni , shruti and nainsi got to know that only the water of the lake that has disappeared long ago can cure their friend 'upasana'. That's why they set out in search of that lake. But the problem was that no one knew where that lake was. Because, that lake existed on this earth a long time ago and no one has seen it for almost 100 years.
Will they be able to find the lost lake?
Will they be able to cure their friend?
How was their journey? What problems did they face?