Best way to queries Database when using two models

Hello guys,

I am trying to get data from one table as an array and use this array to get data from another table. I thought this could be best done with the Eloquent model relationships but I dont know how. So I tried combining the query builders and I got an error. This code is shown below:

public function upvotedStories(){
        $username = Auth::user()->username;
        $liked = WhoUpvoted::where('user', $username)->pluck('story_id');
        $stories = Story::whereIn('id', $liked)->get();
        var_dump($stories);
    }

It gives this error: Argument 1 passed to Illuminate\Database\Grammar::parameterize() must be of the type array, integer given, called in /Applications/XAMPP/xamppfiles/htdocs/storytime/vendor/laravel/framework/src/Illuminate/Database/Query/Grammars/Grammar.php on line 307 and defined

The two tables are whoUpvoted and stories. whoUpvoted has three fields: id, story_id and user. Below is the model for the whoUpvoted:

class WhoUpvoted extends Eloquent {
    protected $table = 'whoUpvoted';
    protected $guarded = array('id');
    protected $fillable = array('story_id','user');

    /*
    / Establishing a relationship with Stories table
    */
    public function story()
    {
        return $this->belongsTo('Story');
    }
}

And for Stories:

class Story extends Eloquent {
    protected $table = 'stories';
    protected $guarded = array('id');
    protected $fillable = array('story','title', 'upvotes', 'author');
    /*
     * WhoUpvoted relationship
    */
    public function whoUpvoted()
    {
        return $this->hasMany('WhoUpvoted','story_id');
    }
}

Is there a best way to solve this using Eloquent models? or What is wrong with the code I have to provoke such an error?

Thanks for your help in advance, Axel.