If you use a second chance then back out, you lose the card, btw
From Fallen London Wiki
Finally got my Scholar up to 10 earlier in the week, kept drawing cards hoping for an Unsigned Letter but finally when TtH showed up I used my Favourable Circumstances to draw it, saw the challenge and used a second chance... when I failed, I thought I could back out and try again at a cost of 2 second chances, as you can sometimes... nope, hitting back on the second chance just closed the card (and I didn't even get the consolation prize from failure ðŸ˜)