Authorize.cs

public async Task<ActionResult> Authorize()
{
    // Get the 'code' parameter from the Azure redirect
    string authCode = Request.Params["code"];

    AuthenticationContext authContext = new AuthenticationContext("https://login.microsoftonline.com/common");

    // The same url we specified in the auth code request
    string redirectUri = Url.Action("Authorize", "Home", null, Request.Url.Scheme);

    // Use client ID and secret to establish app identity
    ClientCredential credential = new ClientCredential(SettingsHelper.ClientId, SettingsHelper.ClientSecret);

    try
    {
        // Get the token
        var authResult = await authContext.AcquireTokenByAuthorizationCodeAsync(
            authCode, new Uri(redirectUri), credential, "https://graph.microsoft.com/");

        // Save the token in the session
        Session["access_token"] = authResult.AccessToken;

        
        return Redirect(Url.Action("Index", "Home", null, Request.Url.Scheme));
    }
    catch (AdalException ex)
    {
        return Content(string.Format("ERROR retrieving token: {0}", ex.Message));
    }
}