diff --git a/PlotLine/Controllers/PlotLinesController.cs b/PlotLine/Controllers/PlotLinesController.cs
index fb2da8c..bf1b28c 100644
--- a/PlotLine/Controllers/PlotLinesController.cs
+++ b/PlotLine/Controllers/PlotLinesController.cs
@@ -32,7 +32,8 @@ public sealed class PlotLinesController(IPlotService plots) : Controller
     {
         if (!ModelState.IsValid)
         {
-            return View("Edit", model);
+            var editModel = await plots.PopulatePlotLineFormAsync(model);
+            return editModel is null ? NotFound() : View("Edit", editModel);
         }
 
         await plots.SavePlotLineAsync(model);
diff --git a/PlotLine/Services/CoreServices.cs b/PlotLine/Services/CoreServices.cs
index c8f167b..7875d97 100644
--- a/PlotLine/Services/CoreServices.cs
+++ b/PlotLine/Services/CoreServices.cs
@@ -113,6 +113,7 @@ public interface IPlotService
     Task<PlotLineListViewModel?> GetPlotLinesAsync(int projectId);
     Task<PlotLineEditViewModel?> GetCreatePlotLineAsync(int projectId);
     Task<PlotLineEditViewModel?> GetEditPlotLineAsync(int plotLineId);
+    Task<PlotLineEditViewModel?> PopulatePlotLineFormAsync(PlotLineEditViewModel model);
     Task<int> SavePlotLineAsync(PlotLineEditViewModel model);
     Task ArchivePlotLineAsync(int plotLineId);
     Task<PlotThreadListViewModel?> GetPlotThreadsAsync(int projectId);
@@ -2099,6 +2100,27 @@ public sealed class PlotService(IProjectRepository projects, IBookRepository boo
         }, lookupData, plotLines.Where(x => x.PlotLineID != plotLine.PlotLineID));
     }
 
+    public async Task<PlotLineEditViewModel?> PopulatePlotLineFormAsync(PlotLineEditViewModel model)
+    {
+        var project = await projects.GetAsync(model.ProjectID);
+        if (project is null)
+        {
+            return null;
+        }
+
+        var lookupData = await plots.GetLookupsAsync();
+        var plotLines = await plots.ListPlotLinesAsync(model.ProjectID);
+
+        model.Project = project;
+        if (model.PlotLineTypeID == 0)
+        {
+            model.PlotLineTypeID = lookupData.PlotLineTypes.FirstOrDefault(x => x.TypeName == "Side Plot")?.PlotLineTypeID
+                ?? lookupData.PlotLineTypes.First().PlotLineTypeID;
+        }
+
+        return await PopulatePlotLineListsAsync(model, lookupData, plotLines.Where(x => x.PlotLineID != model.PlotLineID));
+    }
+
     public async Task<int> SavePlotLineAsync(PlotLineEditViewModel model)
     {
         var isNew = model.PlotLineID == 0;
@@ -2301,7 +2323,6 @@ public sealed class PlotService(IProjectRepository projects, IBookRepository boo
 
     private async Task<PlotLineEditViewModel> PopulatePlotLineListsAsync(PlotLineEditViewModel model, PlotLookupData lookupData, IEnumerable<PlotLineItem> parentCandidates)
     {
-        model.PlotLineTypes = ChapterService.ToSelectList(lookupData.PlotLineTypes, x => x.PlotLineTypeID, x => x.TypeName);
         model.PlotImportance = ChapterService.ToSelectList(lookupData.PlotImportance, x => x.PlotImportanceID, x => x.ImportanceName);
         model.BookOptions = (await books.ListByProjectAsync(model.ProjectID))
             .Select(x => new SelectListItem($"Book {x.BookNumber}: {x.BookTitle}", x.BookID.ToString()))
diff --git a/PlotLine/ViewModels/CoreViewModels.cs b/PlotLine/ViewModels/CoreViewModels.cs
index 6eb537d..1db34ec 100644
--- a/PlotLine/ViewModels/CoreViewModels.cs
+++ b/PlotLine/ViewModels/CoreViewModels.cs
@@ -692,7 +692,7 @@ public sealed class MetricGraphPointViewModel
     public int Percent { get; set; }
 }
 
-public sealed class PlotLineEditViewModel
+public sealed class PlotLineEditViewModel : IValidatableObject
 {
     public int PlotLineID { get; set; }
     public int ProjectID { get; set; }
@@ -704,6 +704,7 @@ public sealed class PlotLineEditViewModel
     [Display(Name = "Type")]
     public int PlotLineTypeID { get; set; }
 
+    [Range(1, int.MaxValue, ErrorMessage = "Choose a plot importance.")]
     [Display(Name = "Importance")]
     public int PlotImportanceID { get; set; } = 2;
 
@@ -726,10 +727,19 @@ public sealed class PlotLineEditViewModel
     public bool IsVisibleOnTimeline { get; set; } = true;
 
     public Project? Project { get; set; }
-    public IReadOnlyList<SelectListItem> PlotLineTypes { get; set; } = [];
     public IReadOnlyList<SelectListItem> PlotImportance { get; set; } = [];
     public IReadOnlyList<SelectListItem> BookOptions { get; set; } = [];
     public IReadOnlyList<SelectListItem> ParentPlotLineOptions { get; set; } = [];
+
+    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+    {
+        if (PlotLineID > 0 && EmergesFromPlotLineID == PlotLineID)
+        {
+            yield return new ValidationResult(
+                "A plot line cannot emerge from itself.",
+                [nameof(EmergesFromPlotLineID)]);
+        }
+    }
 }
 
 public sealed class PlotLineListViewModel
diff --git a/PlotLine/Views/PlotLines/Edit.cshtml b/PlotLine/Views/PlotLines/Edit.cshtml
index 98edcac..8fea696 100644
--- a/PlotLine/Views/PlotLines/Edit.cshtml
+++ b/PlotLine/Views/PlotLines/Edit.cshtml
@@ -37,6 +37,7 @@
 <form asp-action="Save" method="post" class="edit-panel">
     <input asp-for="PlotLineID" type="hidden" />
     <input asp-for="ProjectID" type="hidden" />
+    <input asp-for="PlotLineTypeID" type="hidden" />
     <div asp-validation-summary="ModelOnly" class="text-danger"></div>
     <div class="row g-3">
         <div class="col-md-8">
@@ -44,13 +45,12 @@
             <input asp-for="PlotLineName" class="form-control" />
             <span asp-validation-for="PlotLineName" class="text-danger"></span>
         </div>
-        <div class="col-md-4">
-            <label asp-for="PlotLineTypeID" class="form-label">Type <help-icon key="plotLines.fields.type" mode="inline" /></label>
-            <select asp-for="PlotLineTypeID" asp-items="Model.PlotLineTypes" class="form-select"></select>
-        </div>
         <div class="col-md-4">
             <label asp-for="PlotImportanceID" class="form-label">Importance</label>
-            <select asp-for="PlotImportanceID" asp-items="Model.PlotImportance" class="form-select"></select>
+            <select asp-for="PlotImportanceID" asp-items="Model.PlotImportance" class="form-select">
+                <option value="">Choose importance</option>
+            </select>
+            <span asp-validation-for="PlotImportanceID" class="text-danger"></span>
         </div>
         <div class="col-md-4">
             <label asp-for="BookID" class="form-label">Book / scope <help-icon key="plotLines.fields.scope" mode="inline" /></label>
@@ -69,6 +69,7 @@
             <select asp-for="EmergesFromPlotLineID" asp-items="Model.ParentPlotLineOptions" class="form-select">
                 <option value="">None</option>
             </select>
+            <span asp-validation-for="EmergesFromPlotLineID" class="text-danger"></span>
         </div>
         <div class="col-md-2">
             <label asp-for="SortOrder" class="form-label"></label>