Day 4: Your MC encounters an alien being — what do they do?

Sadie spends a lot of time at the beach, so that would presumably be where she encounters this alien being. Assuming that it isn’t humanoid, Sadie would probably think it came out of the water or from the dunes. If it seems like more of a water creature, she’d try to return it to the ocean (unless it looked dead, in which case she’d leave it for the crabs). Or, if it seemed dangerous, she’d call her sister (who’s a cop) to get someone to take care of it.