Welcome to our Thunderbirds Deep Dives! As we surge towards International Rescue's 60th anniversary, we asked you to pick your favourite episodes of Gerry and Sylvia Anderson's classic 1965 sci-fi adventure series that should receive in-depth, analytical retrospectives. Based on your picks, we've collated a top 10 selection of Thunderbirds greatest episodes to receive a review - as voted for by you!

We're continuing our Thunderbirds Deep Dives with a mysterious string of deadly sabotages of the Red Arrow aircraft which spiral into a torrentially tricky operation for International Rescue.

Operation Cover-ups

Thunderbirds always found creatively appealing methods in depicting the reasoning and methods by which International Rescue maintains its cloak of secrecy. The technologically advanced nature of the Thunderbird machines invites desperate intruders to attempt to obtain their secrets - often with disastrous results. In Donald Robertson's debut episode writing on Thunderbirds, the first of four episodes he'd write, he displays a keen knack for embracing this element of Thunderbirds, and how it comes to impact one of International Rescue's most visually stunning rescue missions.

Secrecy, Elemental Rescues & Brilliant Production Design

Edge of Impact enwraps many distinctive elements into a satisfyingly unified package that expands the history of Jeff Tracy, the secrecy of International Rescue, and the villiany of the Hood - all the while delivering a nail-biting rescue operation. The Hood's nefarious desires to steal International Rescue's secrets to sell them on to the highest bidder is his most defining trait, but this master criminal has other interests. Robertson doesn't portray the Hood as a one-trick pony, as he so often appears elsewhere.

Edge of Impact showcases the Hood in service to other menacing powers, in this case, the elusive General Bron. The Hood has been acquired by Bron to sabotage the efforts of the Red Arrow military jets so that Bron's own dominance of the skies remains unparalleled. The precise backstory of General Bron is left unspoken, but his vaguely defined eastern European accent is one of Thunderbirds' many examples of capturing Cold War anxieties in Supermarionation form. In the far-flung future of 2065, arms races evidently remains in full swing. Watching this episode 60 years on is a firm reminder of the cultural landscape within which Thunderbirds was produced. We see similar power struggles between military leaders at work in The Uninvited and The Cham Cham.

The return of Commander Norman from Trapped in the Sky confirms his positioning as a recurring character throughout the series. Similarly, the reappearance of London International Airport as the launch site of the Red Arrow is a neat reminder of the importance of this location to Thunderbirds' wider canon. The Hood's sabotaging of the first Red Arrow jet gets underway as Colonel Tim Casey, the Red Arrow's project supervisor, is left despondent at the loss of the craft and its pilot when the jet is inexplicably pulled off course on its first test flight. Casey's subsequent visit to Tracy Island is a handsome outreach of friendship towards Jeff. Edge of Impact is the first Thunderbirds episode to allude to Jeff's military history. Where Trapped in the Sky suggests a previous life involving space exploration, this and The Imposters carve out other avenues of his past. It's intriguing that the series delivers Jeff's backstory only in hints and nudges, rarely announcing explicitly described details of his pre-International Rescue life.

Edge of Impact balances the destructive act of the Hood's sabotaging of the second Red Arrow with International Rescue's frozen state of not being able to immediately respond due to Casey's unexpectedly visiting of Tracy Island. Robertson's screenplay neatly dovetails these two elements together, in doing so prizing open Jeff Tracy's elusive pre-International Rescue life when his old army buddy drops in for reassurance before the launching of the second Red Arrow craft. Robertson slides in some pleasingly witty dialogue when Casey presses Jeff as to what he and his five sons do with themselves all day living on Tracy Island, perplexed at their apparent lives of luxury.. 

The episode juxtaposes an engrossingly nervy rescue with the relaxed decadence of scenes set on Tracy Island when the Hood's sabotaging of Red Arrow 2 results in a frightening collision with a British Telecommunications relay tower. International Rescue find themselves prohibited at launching the Thunderbird machines until Tin-Tin can safely lure Colonel Casey out of the way with the playful deception of catching sight of a rare underwater creature around the caverns of the island. From a production design perspective, the visual difference between the luxury of Tracy Island and the starkly isolation of danger zone is brilliantly brought to life, emphasising the series' attention to detail.

Scott, Virgil and Alan's rescue of the two trapped British Telecommunications workers, Jim and Stan, atop the damaged tower is one of Thunderbirds' strangely low-key rescues. Set against a compelling backdrop of darkened skies, blistering winds and torrential rain, the natural elements always make for darkly vivid danger zones. The small-scale nature of the Tracy boys' rescue operation reads like International Rescue being dwarfed by the forces of nature. End of the Road and Day of Disaster had also depicted unstoppable storms, but Edge of Impact marks the first instance of the Thunderbirds operating in the rain, an ambitious and tricky example of practical film-making that would rarely be attempted again.

Robertson's restrained depiction of International Rescue's technology is commonplace throughout his episodes. Where other writers like Alan Fennell delighted in introducing new and impressive pod vehicles or dynamic action from the main Thunderbird craft, Robertson prefers alternative means, showcasing smaller scale rescue tech. Thunderbird 1's remote control camera from Pit of Peril returns, and we see the Booster Mortar deployed for the first time, one of I.R.'s compact, tractor-based vehicles, used to fire Low-Altitude Escape Harnesses to Jim and Stan. Interestingly, much of the rescue is left for the two trapped men to perform themselves, with I.R. unable to reach the perilous heights of the dangerously dizzying tower. 

Just as the tower finally collapses, the men successfully free themselves, despite International Rescue's initial paranoia that they haven't made it out in time. A crescendo of collapsing debris at first masks Jim and Stan's safe passage down to terra firma. Virgil's passing line of "This is the first time International Rescue has failed" is a striking acknowledgement that for all the breath-taking heroics International Rescue regularly perform, all it can take is a split second for a rescue to become a nightmare. Less successful is the Hood, whose tracking device used to draw the Red Arrow off course is discovered by Virgil and his subsequent attempts to outrun the ensuing police pursuit ends in typically Looney Tunes fashion, as it so often does for the Hood.

"Thanks, Jeff Tracy"

Edge of Impact concerns itself with depicting plenty of advances in military and civil engineering - accompanied by their subsequent vulnerabilities. From technologically superior aircraft to the growing reliance on electronic communications, the episode showcases extreme anxieties of Thunderbirds' futuristic world when it's subject to sabotage and disaster. Robertson's screenplay also showcases how International Rescue operates within its cloak of secrecy and highlights Jeff's life outside of the organisation, a humanising touch amid the episode's sprawling array of technological disasters.

From insightful character backgrounds to Cold War-tinged jeopardy, Edge of Impact showcases many of Thunderbirds' most winning elements produced in a hugely satisfying package of dramatic rescue adventure.

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