They started this venture in 1999 with an experimental story which would determine whether or not the BBC would allow them full access to the Classic Era of Doctor Who. It was called The Sirens of Time and rather than risk losing their one shot at Doctor Who and putting their faith in one Doctor, Big Finish opted to make this chance count by busting out three Doctors, namely the Fifth, the Sixth and the Seventh.
The Sirens of Time has the reputation of being one of the weaker stories in Big Finish's repartee, but keep in mind that it was good enough for the BBC who had axed Doctor Who before.
Personally, I love The Sirens of Time. Partly because of the multi-Doctor format, but also because I love the Sixth and Seventh Doctors. Don't get me wrong, I love all of them, but those two...magnificent.
As for the story itself, it does quite a lot of things correct. First of which is the villain and the tension that sort of parallels it. It's a case of hidden in plain sight, but it also takes advantage of the audio format and that the audience can't see what's going on, which makes the eventual reveal all the better.
Each episode focuses on one Doctor and their encounter with the Sirens of time, though this isn't always clear. They do have their multi-Doctor encounter and back and forth banter, but unlike The Day of the Doctor, its not as funny or in your face. The Fifth, Sixth and Seventh Doctors actually work pretty well together, but they are not above delivering verbal jabs at one another.
This story also concerns Gallifrey, a setting that is rare in Doctor Who, thus makes the story look more attractive to first time listeners. I didn't mind Gallifrey's involvement. The setup was well handled and their dilemma reminds one of The Three Doctors. Again, this story had to pull out all the stops in order to get people to buy the story.
The weakest aspect of this story is probably Maggie Stables character. A horrendous accent and the dialogue is terrible. Stables didn't have a chance making her seem real or anything more than a campy joke. Thankfully she isn't as prominent a character so I'll let that one slide.
Rating this story: 4/5.