relative path in Import-Module

When you use a relative path, it is based off the currently location (obtained via Get-Location) and not the location of the script. Try this instead:

$ScriptDir = Split-Path -parent $MyInvocation.MyCommand.Path
Import-Module $ScriptDir\..\MasterScript\Script.ps1

In PowerShell v3, you can use the automatic variable $PSScriptRoot in scripts to simplify this to:

# PowerShell v3 or higher

#requires -Version 3.0
Import-Module $PSScriptRoot\..\MasterScript\Script.ps1