// Starts the story currently selected in the library.
    private void onReadButtonClick()
    {
        // Read the selected value of the story dropdown and start that story.
        LibraryBook selectedBook = this.libraryBooks[this.selectedLibraryBookIndex]
                                   .GetComponent <LibraryBook>();

        this.hideElement(readButton.gameObject);
        // Send ROS message.
        bool needsDownload = !this.assetManager.JsonHasBeenDownloaded(selectedBook.story.GetName());

        if (Constants.USE_ROS)
        {
            this.rosManager.SendStorybookSelected(needsDownload).Invoke();
        }
        this.startStory(selectedBook.story);
        selectedBook.ReturnToOriginalSize();
    }