You Do Need power plug adapter while traveling from South Sudan to Montserrat.

Here is Why You Need An Adapter

The outlet and plug type used in Montserrat are A and B and in South Sudan are C and D. This is how they look like.

South Sudan

In South Sudan, outlets of type C and D are in use.

Type C

Type D

Montserrat

In Montserrat, outlets of type A and B are in use.

Type A

Type B