In2016,ayoungAustralianfilmmakerbegandocumentingamateurinventorPeterMadsen.Oneyearin,MadsenbrutallymurderedKimWallaboardhishomemadesubmarine.Anunprecedentedrevelationofakillerandthejourneyhisyounghelperstakeastheyreckonwiththeirowncomplicityandpreparetote