Reloading of layout causes Model to go empty (MVC4) - asp.net-mvc-4

Question

I'm trying to show a table of results in my view by use of HttpPost, but my view always turns up empty.
I have found out by now that the httpPost action works and returns a result, but before completing the action, the layout is called again, where the RenderBody is called again. Once the RenderBody is done, the view contains an empty model again and results in the page showing up empty.
Looking for advice how to solve this issue! I broke my head on this for hours and don't seem to see the light...
The View code:
#using MovieRental.DAL.Entities; #model List
<Movie>
#{ ViewBag.Title = "MyRentedMovies"; }
<h2>MyRentedMovies</h2>
<div class="container">
<div class="col-md-12 column">
<form id="frmmymovies" class="col-md-12">
<input id="currentuserid" type="hidden" name="userid" value="#ViewBag.user.UserId">
</form>
<div id="mymovies" class="btn btn-primary">Show my rented movies</div>
</div>
</div>
<div>
#ViewBag.cost;
</div>
#if (Model != null) {
<div class="container">
<div class="row clearfix">
<div class="col-md-12 column">
<table id="" class="table table-striped table-bordered">
<thead>
<tr>
<th>Action</th>
<th>Movie Title</th>
<th>Release Date</th>
<th>Storyline</th>
<th>Location</th>
<th>Movie Genre</th>
</tr>
</thead>
<tfoot>
<tr>
<th>Action</th>
<th>Movie Title</th>
<th>Release Date</th>
<th>Storyline</th>
<th>Location</th>
<th>Movie Genre</th>
</tr>
</tfoot>
<tbody>
#foreach (var item in Model) {
<tr>
<td><i class="glyphicon glyphicon-plus" movieId="#item.MovieId"></i>
</td>
<td>#item.MovieName</td>
<td>#item.ReleaseDate</td>
<td>#item.Storyline</td>
<td>#item.Location.LocationName.ToString()</td>
<td>#item.MovieGenre.GenreName.ToString()</td>
</tr>
}
</tbody>
</table>
</div>
</div>
</div>
} else {
<div class="container">
<div class="row clearfix">
<div class="col-md-12 column">
<div class="alert alert-info" role="alert">
You currenty don't have any rented movies in your possession.
</div>
</div>
</div>
</div>
}
The Controller code:
public ActionResult MyRentedMovies()
{
return View();
}
[HttpPost]
public ActionResult MyRentedMovies(int userid)
{
var myrentdetails = rentrep.GetAll().Where(e => e.UserId == userid);
List<Movie> mymovies = new List<Movie>();
foreach (var item in myrentdetails)
{
Movie movie = movierep.FindById(item.MovieId);
mymovies.Add(movie);
}
return View(mymovies);
}
The JS script:
$(function () {
$('#mymovies').click(function () {
//var user = $('#currentuserid').val();
console.log('gethere');
$.post('/useronly/myrentedmovies', $('#frmmymovies').serialize(), function (data) {
if (data) {
console.log(data);
document.location = '/useronly/myrentedmovies';
}
else {
console.log('error');
}
});
});
});