I had a try
found it but can't link
Joe suggested
The Tony/Cassandra adventures - they're fun, fast-paced. They're basically their own series - private investigator Tony Peterson and the witch Cassandra (aka Angelique) work together to solve supernatural mysteries. Although each one works well on its own, there's a nice character journey throughout the stories - so they're a good series to listen to in order. They're set in the early to mid 1970s.
16. The Death Mask
22. The Voodoo Amulet
29. The Last Stop
33. The Phantom Bride
43. The Devil Cat
Then move onto:
The Quentin adventures - Quentin was a bloke in 1897 who was a bit of a rogue. A gypsy turned him into a werewolf but then a warlock gave an artist supernatural powers to subdue the werewolf curse. Which also made him immortal. So he was a werewolf and now he's Dorian Gray. Again, they're a series of mostly standalone adventures but with some nice character stuff if you listen to them in order. You don't need to know the backstory but basically Quentin left Collinsport after missing the love of his life Amanda Harris at a train station. So he's searching for her. He will eventually return to Collinsport in 1969 but with no memory of who he is and calling himself Grant Douglas. These adventures are set while on his travels. So he leaves Collinsport in 1897 and...
05. The Skin Walkers
11. Blood Dance
13. London's Burning
17. The Creeping Fog
27. Operation Victor
You can then listen to:
25. The Eternal Actress
which tells the story of Quentin's long-lost love - Amanda Harris (she's also immortal btw).
Quentin and Amanda are then reunited in:
44. The Darkest Shadow
which leads into:
31. The Haunted Refrain
And then you can go onto:
15. The Blind Painter
which tells the story of Charles Delaware Tate - the artist who gave Quentin immortality and who created Amanda Harris. The Blind Painter also introduces the character of bonkers gypsy Ivanka Romano. Ivanka's story continues in:
21: The Crimson Pearl
which features pretty much everyone and everything but should make sense - especially if you've heard the previous adventures. Ivanka then returns in:
32: A Collinwood Christmas
which continues Ivanka's story and sees her joining forces with Jamison Collins - Quentin's beloved nephew.
Other characters from 1897 (Quentin's time) have their own stories to tell...
The mad, evil Reverend Trask was bricked up in one of the rooms – by Judith Collins (Quentin's sister), with just a gun for company, in the TV series. His story continues in:
07. The Wicked and the Dead
which then continues into:
18. The Carrion Queen
which sees Trask in battle with Angelique (aka Cassandra!)
Trask's daughter, the quiet reserved Charity, was left possessed by the spirit of Pansy Faye (sister of Rosie from London's Burning) in the TV series. Their story continues in:
19. The Poisoned Soul
And then the Trasks' story continues in:
26. The Fall of the House of Trask
And then there are the continued adventures of the modern-day (1960s/70s) characters such as Maggie Evans...
Her first stay at Windcliff Sanitarium (set during the TV series) is told in:
03. Clothes of Sand
which also tells us much about her childhood and character and so on.
When she left the TV series it was to stay at Windcliff again. What happens next is told in:
04. The Ghost Watcher
The story of what happened to Sebastian Shaw, who took Maggie to Windcliff, is told in:
30. Dreaming of the Water
Carolyn, Maggie's friend and the daughter of the house of Collinwood, continues her story in:
09. Curse of the Pharaoh
Her character also features in:
23. The House By The Sea
After this, there's a run of stories featuring Maggie, Carolyn and the other residents of 1970s Collinsport:
34. Beneath The Veil
35. The Enemy Within
36. The Lucifer Gambit
37. The Flip Side
38. Beyond The Grave
40. The Harvest of Souls
41. The Happier Dead
42. Carriage of the Damned
Many of these characters return in the full-cast audios (set about ten years later).
1.1. The House of Despair
1.2. The Book of Temptation
1.3. The Christmas Presence
1.4. The Rage Beneath
2.0. Kingdom of the Dead
3.0. Snowflake
3.1. Bloodlust
The dramatic readings from 45. Panic through to 50. ...And Red All Over then follow on from here.
The full cast audios also feature the character Barnabas - who, years later, sums up his life story in:
12. The Night Whispers
The love of Barnabas's life was Josette (you'll hear her music box a lot throughout the series). The story of what happened after she died is told in:
10. Final Judgement
20. The Lost Girl
By this point, you'll have heard a few other characters mentioned and some of their stories are told in...
39. Curtain Call
This is the story of Leticia Faye (related to Pansy and Rosie from the earlier audios). She's a retired psychic who is persuaded to step onto the stage once more.
14. The Doll House
Before Quentin left Collinwood in 1897, he'd previously run off with his sister-in-law. His wife went mad and was locked up in the tower room. This is her story. It also features the character of bitter, miserable Judith (the one who'd end up locking Trask up with just a gun for company - it all links!). Judith wasn't always so uptight though... Her teenage years are told in:
24. Dress Me In Dark Dreams
which features Judith's great-grandmother, Edith. Edith also had a nephew, Tad. And Tad's story is told in:
28. Speak No Evil
And that leaves us with:
06. The Path of Fate - which sees Quentin joining forces with Angelique in 1990.
and
08. Echoes of Insanity - which tells the story of Willie Loomis's stay at Windcliff
And now, if you think you're ready, it's time for the full story of Angelique before she became Cassandra...
01. Angelique's Descent