Doctor Who’s Ruth twist was a groundbreaking swerve for the iconic science fiction series, but the episode left a trail of breadcrumbs to tip viewers off to the shocking reveal. In season 12’s “Fugitive of the Judoon,” the titular rhino-shaped space thugs descend upon Earth under contract to find a specific runaway. The Thirteenth Doctor eventually identifies their target as Ruth, a harmless British tour guide with no idea why the Judoon are chasing her. With fans still reeling from the long-awaited return of Captain Jack Harkness (this episode wasn’t doing things by halves), another bombshell dropped - Ruth was a regeneration of The Doctor.

This version of The Doctor had been working in an unknown capacity for some shady Gallifreyans and tried to run away, ultimately deciding to use the TARDIS’ chameleon arch to replace her Time Lord identity with a human one, until the arrival of the Judoon forced Ruth to restore her true self. Most fascinatingly of all, Ruth has no recollection of ever looking like Jodie Whittaker, making it unclear whether this is a future Doctor, as one might expect, or a hidden past regeneration.

So many questions regarding the Ruth Doctor remain unanswered but, as surprising as the twist was, “Fugitive of the Judoon” smartly foreshadowed Ruth’s true identity throughout the episode. Here are all the clues Ruth and The Doctor are one and the same.

Staring At Time

The true nature of Ruth’s identity is teased in “Fugitive of the Judoon”’s very first scene, in which the audience see Ruth silently staring at a clock face. This image immediately creates a connection between Ruth and time, hinting that she’s a Time Lord at the very least, if not specifically The Doctor. There’s an implication that Ruth is waiting for something, which makes sense given her later emergence from the influence of the chameleon arch. More interesting, however, is the exact time Ruth snaps out of her trance - eight o’clock. A hint towards her regeneration number perhaps?

Ruth’s Job

Although it may not be an obvious clue by itself, Ruth’s occupation makes complete sense given that she’s secretly The Doctor. When David Tennant’s Tenth Doctor used the chameleon arch in “Human Nature,” his alter ego was a teacher, which suited the character’s personality. A tour guide with a budding knowledge and passion for the past is just as appropriate.

“Not A Nickname”

The introduction of All Ears Alan provides several clues towards Ruth’s identity. Firstly, the fact that a man in a coffee shop presents Ruth with a dossier on her partner and she doesn’t immediately call the police is strange. Of more significance is when Ruth tells Alan, “it’s not a nickname if you give it to yourself.” It was confirmed previously in Doctor Who that The Doctor chose their own title before leaving Gallifrey, putting a distinctly ironic twist on Ruth’s words to Alan.

Standing Up To The Judoon

When the Judoon first touch down in Gloucester, everybody runs apart from Marcia, who’s old and stubborn, and Ruth. Not only that, the hidden Time Lord verbally stands up to the space police when they strike down her aged friend, chastising them in a way few real humans would do when faced with an alien invasion. This moment provides an early hint that Ruth is perhaps more used to dealing with Judoon platoons than one might assume.

Ruth & Lee’s Flat Design

As pointed out by RadioTimes, the design of Ruth and Lee’s Earthling flat bears a number of aesthetic similarities to the TARDIS. There’s the same familiar dark blue color featured on the couch and the windows are reminiscent of those on the TARDIS doors. Most obvious, however, is the hexagonal mirror that teases the classic central console of The Doctor’s ship. All of the hints are subtle, but if The Doctor was going to rent a flat in 21st century England, this is probably what it’d look like.

Commander Gat

Doctor Who’s biggest Ruth clue up to this point comes with the arrival of Commander Gat. Although her attire doesn’t consist of the telltale headpiece and ruby red robes that would’ve immediately said “Time Lord,” Gat’s attire is consistent with previous Gallifreyan costumes. The black skullcap type business can be seen in classic-era Doctor Who, worn by Time Lords of high standing, while her black cloak is very similar in style to that worn by the Valeyard. In another major clue, Gat refers to Lee as a “faithful companion,” purposely using the same term The Doctor uses for her friends.

Ruth’s Flashbacks

Throughout “Fugitive of the Judoon,” Ruth begins suffering flashbacks to the lighthouse and the fire alarm that is eventually revealed to house her true identity, with the reveries mostly coming during times of stress or when Ruth is faced with some alien reminder. This is exactly what happened when the Tenth Doctor used the chameleon arch. As “John Smith,” Tennant’s Doctor would have dreams about his former life and visions about the fob watch that contained his Time Lord self. The watch “called” to The Doctor, similar to how the lighthouse seems to for Ruth. In another parallel to “Human Nature,” Ruth is scared when she first gets a glimpse of The Doctor, and is reluctant to change back. Exactly the same hesitation occurred when John Smith transformed back into the Tenth Doctor.

Ruth’s Reaction To Lee’s Death

Viewers might’ve expected Ruth to be distraught when the Judoon revealed her partner had been murdered, but Whittaker’s Doctor seemed more bothered than she did. The steely, composed expression on Ruth’s face while she watches Lee’s death is a sure sign that this mystery woman has experienced her fair share of bloodshed, but it’s her rallying cry against bullies that rings familiar alarm bells, mirroring sentiments The Doctor has shared many times. And then there’s the “Jackie Chan” impression… Venusian Akido, anyone?

Eighth Doctor Connections

Ruth jumping into action when the clock struck 8 in her very first scene is far from the only connection between her and Paul McGann’s Eighth Doctor. When heading to the lighthouse, Ruth and Whittaker drive down in what is assumed to be Ruth’s car. The vehicle in question is a Volkswagen Beetle, the same type of car driven by McGann’s Doctor in his canon audio adventures. Ruth later tells her fellow Doctor that she arrived in Gloucester in December 1999, the exact period the Eighth Doctor’s TV movie was set. Coincidence? Or a clue to where Ruth comes in The Doctor’s history?

“One Of Those Faces”

By the episode’s final third, Doctor Who is beginning to toy with the audience with regards to Ruth’s identity and, while in the Beetle, Ruth questions why she’s putting so much trust in The Doctor. Without missing a beat, Whittaker replies, “I’ve just got one of those faces.” Perhaps unknowingly, this applies to The Doctor just as much as it does Ruth. Despite seeing her take down Judoon soldiers, The Doctor continues to believe Ruth’s amnesia is real, proving she must have “one of those faces” too.

The Fire Alarm

As the final reveal becomes imminent, Doctor Who drops two massive clues about Ruth’s identity. The first are the Gallifreyan markings etched around the fire alarm that Ruth breaks to restore her identity, and the second is the giveaway golden Time Lord mist energy that flows into her. These visuals are both highly reminiscent of Tennant’s revival from the chameleon arch and the regeneration energy fans have become increasingly used to seeing flow out of The Doctor’s limbs when changing into a new actor.

More: Doctor Who Season 12 Creates A Historical Adventure Plot Hole

Doctor Who continues with “Can You Hear Me” February 9th on BBC and BBC America.