Load external assemblies into new app domain and call a method of "base class"

I'm new to remoting in .NET (which I believe this is related to).

Assume that main application references a class library A which contains an abstract class with an abstract method.

Now, assume that we create an entire new project B and reference the same DLL A, make a new class that inherits the abstract class and implements the method.

Is it possible to load this new assembly into a new appdomain in the main application and create an instance only knowing the base class type?

Or is there a better way? I'm thinking of some sort of plugin system here.