The Secret in the Cellar (2021)

Jack, Jess, Jo and Josh gather in their family home just after burying their mother. Never one for niceties, she's left each one a letter bound to incite division amongst them. She's left a key for her favourite, Jess, which leads them down into the spooky old cellar of bad memories. Down there, they find an old trunk, large enough to contain a body; what could possibly be in there? And where did their dad disappear to years ago?