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

Here is Why You Need An Adapter

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

Montserrat

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

Type A

Type B

Zambia

In Zambia, outlets of type C, D and G are in use.

Type C

Type D

Type G