I'm running a Homebrew one shot (hopefully to lead to a full campaign) loosely based on Firefly. It'll be a basic artifact retrieval situation, the deal is that a client has defaulted on a payment for a powerful magical item and my party has been tasked with retrieving it, glorified repo agents. It was my intention to have them go into a spooky mansion of some kind to retrieve it from some kind of reclused warlock or mage. I wondered if there were any modules knocking about that might make this easier to put together.

There’s the 1e module castle amber. Goodman games is releasing a 5e update set for September, last I heard. 
But if you can’t wait, you could track down the old version and update it yourself, probably. 

you could try The Haunt, an adventure on dmsguild.

Quote from Xalthu >>

There’s the 1e module castle amber. Goodman games is releasing a 5e update set for September, last I heard. 
But if you can’t wait, you could track down the old version and update it yourself, probably. 

 There was also an AD&D2e sequel called Mark of Amber, that would probably be easier to update to 5e.

Cool, I'll check it out! Thanks! I just need ideas anyway.