Five college graduates seek one final adventure together before real life gatecrashes their worlds in a tense survival thriller directed by Jeff Wadlow. Good friends Adrienne (Tommie Rose), Greg (Gavin Casalegno), Max (Lana Condor), James (Nico Hiraga) and Sara (Kathryn Newton) are determined to enjoy one final summer hurrah before they are forced to accept the responsibilities of adulthood. The quintet venture to Thailand and sign up for a swim through a remote cave system known as The Devil's Mouth led by trusted guide Wat (Tayme Thapthimthong). Wat shepherds the friends through the labyrinth of narrow waterways where the interlopers discover a recent freak storm has brought a deadly predator into the caves. Panic surfaces as Adrienne, Greg, Max, James and Sara realise they are being hunted by a silent killer and the only way to escape is to venture into the water