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

Here is Why You Need An Adapter

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

Gabon

In Gabon, outlets of type C are in use.

Type C

Montserrat

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

Type A

Type B