C++ :: Calculating depth Of Binary Tree

i have come across this code for calculating the depth of a binary tree.

int maxDepth(Node *&temp) {
if(temp == NULL)
return 0;
else {
int lchild = maxDepth(temp->left);
int rchild = maxDepth(temp->right);

[Code] ....

In these recursive calls i am really clue less about how the statements i numbered from 1 to 4 would be executed...in every recursive call...???

Lets temp has left depth of 3 and right depth of 100 then...in last 97 recursive calls max(temp->left) would be doing...????? how these recursive mechanism work here... I want to know specifically how these left node and right node recursive calls are co-ordinating with each other????