### Solution:> If we open the page ([https://hidden.challenges.nactf.com/]()), we see a blank green page.  > > ![](https://media.discordapp.net/attachments/771504940623331378/773704557477232660/unknown.png)  > > Open up the Inspector Tools again, go to Elements Tab (default tab), and expand everything. We can see that there is a link to an image that wasn't shown on our page. If you notice, the file path is "challenges.nactf.com/flag.png", and the "hidden" portion is not included.  > > ![](https://media.discordapp.net/attachments/771504940623331378/773710787264249907/unknown.png)  > > We need the "hidden" subdomain part of the URL for the image to be successfully called. If you fix the "img" HTML tag or open the link in another tab, you will get the image with the flag.  > > ![](https://media.discordapp.net/attachments/771504940623331378/773715048618000394/unknown.png) #### **Flag:** nactf{h1dd3n_1mage3s}