Archive Status: Both episodes exist in color as PAL 2" videotape, as held by the Film & Videotape Library when audited in 1978.

Tom Baker (Doctor Who), Elisabeth Sladen (Sarah Jane Smith), Ian Marter (Harry Sullivan), Kevin Lindsay (Styre), Glyn Jones (Krans), Donald Douglas (Vural), Peter Walshe (Erak), Peter Rutherford (Roth), Terry Walsh (Zake), Brian Ellis (Prisoner)

Arriving on a desolate and windswept Earth the Doctor starts realigning the transmat refractors while Sarah and Harry go off to explore. Harry slips and falls into a pit and Sarah runs back to the Doctor to get help. The Doctor, however, has been captured by a trio of shipwrecked Galsec space travellers who were lured to Earth by a phoney distress call. Sarah, unable to find the Doctor, makes friends with a fourth space traveller, Roth, who tells her of the alien in the rocks who is experimenting on them. Before long, Sarah and Roth are recaptured by a robot and dragged off to the rocks.

Harry finds his own way out of the pit via a series of underground tunnels and emerges close to an outcrop of rock. He watches as Sarah and Roth are presented to the alien who turns out to be a Sontaran.

Field-Major Styre is part of the Sontaran G3 Military Assessment Survey, experimenting on the humans to try and determine their resistance to battle as Earth had now taken on a strategic importance in the Sontarans' ongoing war with the Rutans. The Doctor interrupts Styre's experiments and challenges him to unarmed combat. The Sontaran readily agrees but has not realised that Earth's unfamiliar gravity will give the agile Doctor the advantage. While the Doctor is keeping Styre occupied, Harry enters the alien's spacecraft and removes the terrulium diode bypass transformer, so that when Styre, exhausted by the fight, returns to revitalise himself, he is instead destroyed, drained of all his energy.

As a final warning to the main Sontaran fleet, the Doctor sends a message to them, telling of their emissary's destruction and warning that without Styre's report they cannot know the strength of human resistance and so had better look elsewhere - brinkmanship at its most effective.

The Doctor and his friends use the transmat with the intention of returning to the beacon - they have good news for Vira.

Synopsis from Doctor Who: The Fourth Doctor Handbook by David J. Howe, Mark Stammers and Stephen James Walker, reprinted with permission; further reproduction is not permitted.

Russ Karel (Assistant Floor Manager), Barbara Kidd (Costumes), Roger Murray-Leach (Designer), Terry Walsh (Fight Arranger), Dudley Simpson (Incidental Music), Sylvia James (Make-Up), Philip Hinchcliffe (Producer), Marion McDougall (Production Assistant), George Gallacio (Production Unit Manager), Robert Holmes (Script Editor), Dick Mills (Special Sounds), Delia Derbyshire (Theme Arrangement), Ron Grainer (Title Music), John Friedlander (Visual Effects), Tony Oxley (Visual Effects)

The return of the Sontarans marked the only two-part story in the 1970's. Kevin Lindsay, who had originated the Sontaran role Linx in "The Time Warrior," returned here to play Styre and the Sontaran Marshal; actor Glyn Jones (Krans) had written the serial "The Space Museum" during the Hartnell era. Tom Baker broke his collarbone during the making of this story and his neck brace was masked with a scarf and coat; Terry Walsh doubled for him during action sequences. The entire story was entirely shot on OB (outside broadcast) video, the first time in the series history that this was done, and was made entirely on location. The original working title of the story was 'The Destructors' and was changed to the current title under protest by the writers, who felt it gave the cliffhanger away.

Due for DVD release in the UK in October 2006; Australia/New Zealand and US/Canada release dates unannounced. No confirmation of specific inclusions on DVD besides the two episodes.

Released as “Genesis of the Daleks/The Sontaran Experiment” two-tape set in the UK [October 1991] and Australia/New Zealand [July 1992] (BBC catalog #4643), US/Canada [February 1994] (WHV catalog #E1201); episodic format, cover illustration by Andrew Skilleter.

Novelised as “Doctor Who and the Sontaran Experiment” by Ian Marter (Target #56), hardcover and paperback, first released in 1978 with cover art by Roy Knipe.

For more details on the various novelizations of this story, with additional background material, artwork and details of both UK and foreign releases, visit On Target.