The story is a very loose take on Robert Louis Stevenson’s story. We have set it in 1905, with a hospital as the main setting.
Henry Jekyll is a doctor, an avuncular figure who runs a moderately successful hospital in Barking. He is assisted by Miss Anne Thrope, the Matron (principal villainess) and Lulu Lather (the dame), who runs the hospital laundry. Crowds of patients go in and out of the hospital every day.
Also around are Molly O’Loan, Miss Thrope’s downtrodden ward and the heroine. Jack, the hero, is the son of Lulu Lather. Molly is bookish and intelligent, sneaking out of the watchful eye of her guardian to read books in Jekyll’s library at night. Jack also prowls the hospital at night, but his main aim is mischief. He is prankish and a bit immature.
Meanwhile, two incompetent criminals, Burke and Head (one male, one female), slope around the hospital, pinching things.
After a busy opening number setting the scene and introducing Jekyll and his patients, we learn of Jekyll’s desire to create a super-potion, a fabulous cure-all. We see him take it in his laboratory. He shakes, sweats and converts into the amoral Hyde (played by a different actor). Hyde loves chaos, and causes it with the audience at his first appearance. After a short time he converts back into Jekyll with no memory of being Hyde. Convinced his potion is a success, he decides to start mass production.
Lulu Lather is introduced, in her laundry. She likes the job because it enables her to wear other people’s clothes and pretend she is someone grand and impressive, or someone funny – so long as she doesn’t have to be herself she’s happy. (Song: Pretty Little Dresses). Miss Thrope, who does not like Lulu’s pretensions above her station, comes in and argues with her, but both women are sweetness and light when Jekyll arrives.
Jack and Molly bump into one another while both investigating Hyde’s vandalism. They don’t exactly hit it off. Molly thinks the answer to every mystery can be found in books, and Jack believes in seeing things for himself. After being tricked by him Molly sings a sad song about her loneliness (Song: Molly O'Loan).
Called in to investigate the vandalism, Sheerluck Jones, the greatest detective in London (according to himself) or a pompous, incompetent bumbling twit (everyone else) arrives with his sidekick PC Poo. Every conclusion is wrong, and he is highly suspicious of Jack. (Song: I Always Get My Man)
Jekyll invites the others to witness the unveiling of his new Essence Distillation Engine, which he will use to synthesise his potions. It’s a crazy, Heath Robinson contraption. (song: Essence Distillation Engine). It separates things into their component parts.
Next, we find Miss Thrope doing a dirty deal with Burke and Head. They’ve been snaffling things from the hospital and passing the money back to her in exchange for her connivance. They’re not as competent as they’d like though. Matron complains bitterly about how frustrated she is in a subordinate role to the too-kind Dr Jekyll.
Jekyll, alone once more, takes more potion and turns into Hyde. This time Hyde smashes up the precious medical library. Torn pages fly everywhere. Miss Thrope discovers Hyde in Jekyll’s laboratory but instead of turning him in as the hospital’s mystery vandal, she sees in him a kindred spirit and they plot to do evil together. (song: Dog With a Bone).
Jekyll soon sees ink on his own fingers, that reveals to him that he (as Hyde) is the perpetrator of the vandalism. He is terrified by what he has done, and by the thought of an evil personality he cannot control (song: Dual). He sings a solo, but is soon joined by Hyde’s voice, and then a multiplicity of confusing voices inside his head. Against his better judgement, the voices play on the allure of the potion and he succumbs, taking another dose. Hyde is free once more.
Lulu (sacked by Miss Thrope) packs her belongings, but is then terrorised by Hyde. He attacks her but is suddenly incapacitated as the potion starts to wear off. Lulu runs away, and Miss Thrope arrives, warning Hyde to be more careful, but as she watches, the man she thought was her soulmate converts back into her enemy – Dr Jekyll.
Jekyll runs to the distillation cabinet and puts himself in it to try and cure himself, but it separates him into his two component parts. Hyde and Jekyll are now two separate people, one wholly good, one wholly evil. Miss Thrope seizes the opportunity to capture Jekyll. Hyde, with Miss Thrope as his mentor is now in charge of the hospital. (song: Hyde Triumphant).
Act II A montage number (Corruption) sets the scene again. Hyde is creating more of Jekyll’s potion to convert more people into evil versions of themselves - an army of evil-bent soldiers with no memories for him to control.
Molly secretly rescues Jekyll from under the noses of Burke and Head. Meanwhile, Lulu, impersonating the Duchess of Cleveland (her last disguise now that she has been fired from her laundry), goes to visit Sheerluck Jones at the nick. She manipulates his snobberies and ardour (they sing a romantic duet: I Know My Station) and manages to sneak Jack out under her skirt.
Jekyll and Molly go disguised to the hospital where Hyde is feeding all his patients potion. They cause chaos by mixing up all the potions, leading to all kinds of bizarre behaviour from the patients. (this is a big company number: Going Through The Potions). They make Hyde waste his potion because he continually has to dose the same patients, after the other potions cancel out the effects of the evil potion. Hyde runs out of potion.
Miss Thrope manages to uncover Jekyll and Molly. There is a big chase sequence (another company number: Chase and Capture). Molly escapes but only at the cost of Jekyll being captured by one of the potions. He is captured by Hyde. Hyde discovers that hitting Jekyll causes Hyde pain. But Hyde needs Jekyll’s expertise to manufacture more potion. Jekyll, under duress and underground beneath the hospital, is building a giant Essence Distillation Engine mk. 2 for Hyde to use in potionmaking.
Miss Thrope bewails the waste and complains to the audience that every time she teams up with a man he proves incompetent (song: Those Men)
Finally, Lulu, Jack and Molly are together and can work on a scheme to stop Hyde. Molly has learned that sometimes playing pranks can be practical (as when she swapped the potions around), but if they are to succeed, Jack needs to learn how to apply knowledge from books. They go to the library and we see Jack moving from being a difficult student to realising his potential under Molly’s tutelage. (song: Model Pupil)
Sheerluck finally realises that the ‘Duchess of Cleveland’ was no such person and sets off in hot pursuit of Lulu.
Molly and Jack finally have a plan to rescue Jekyll and stop Hyde. It’s complicated so it takes a fast-paced song (song: Bringing it Together) to explain it to Lulu and the audience. Luckily, Burke and Head are guarding the hospital door, and they are arguing about their future. Burke wants to go on doing crime, but Head wants to settle down. It is easy for Jack and Molly to fool them and slip in.
Lulu, however, is left outside by mistake. Seeing that Sheerluck has nearly caught up with her, she must abandon her final disguise to evade capture. Not only that but she has to abandon her pretensions too in order to follow Jack and Molly by way of the sewer. She finally realises she has to be herself. (song: Underneath These Starches).
The Essence Distillation Engine mk. 2 is complete, so massive it takes up a whole wall of the underground cavern beneath the hospital. But Jekyll cannot allow the potion to be made. At the crucial moment, he threatens to throw himself into the machine, which would hurt Hyde. There is a stand-off. Miss Thrope however, ruthlessly throws both men into the machine and starts to operate it.
Molly and Jack arrive, only to discover their plan, perfect in theory, to rescue Jekyll has been pre-empted. It is time to improvise. Sheerluck arrives and there is a frantic three-way battle between the heros, Sheerluck and Miss Thrope. Finally, Jack manages to throw the machine into reverse, causing it to collapse in a shower of sparks, smoke and light. Jekyll, now recombined into one, staggers out. Matron, having taken the wrong potion in the chaos, is now only 3 foot tall (played by a child). Burke and Head opt for domestic life after all and adopt her. Molly and Jack tell each other they’ve fallen in love.
It’s time for the audience to help Jekyll regain his memory (traditional audience participation song), and finally for Jekyll and Lulu to realise, together, that rather than trying to be someone or something else, you are better off learning how to be you. (song: You Are Everything You Need). The company finally whip off their surgical gowns and sing the Finale/Walkdown together (Bringing it Together reprise).