You Do Need power plug adapter while traveling from Lesotho to Monaco.

Here is Why You Need An Adapter

The outlet and plug type used in Monaco are C, E and F and in Lesotho is M. This is how they look like.

Lesotho

In Lesotho, outlets of type M are in use.

Type M

Monaco

In Monaco, outlets of type C, E and F are in use.

Type C

Type E

Type F