After Dark

3 friends skip a football game and go to the nearest park to hangout.

Soon after the first visit one of them ends up dying. Cause: Drowning
Body: Yes

They try to figure the death knowing it wasn't an accident after getting a big clue the next one dies,
Cause: Suffocation
Body: Yes

The final friend brings in their two other friends to help with the investigation after finding out the deaths of their friends the third friend is found dead
Cause: Unknown
Body: None to be found

Is it a monster? Or just plainly an accident?

(COVER IMAGE IS NOT MINE)