The fifth season of Castle has finally kicked into high-gear, and the point of focus isn’t everyone’s favourite recurring theme; with Senator Bracken’s ongoing evasion of justice brought up and dismissed again only two weeks ago, it seems there’s something else in store. This episode begins as a somewhat slow-paced hit-and-run investigation, but rapidly evolves into an emotionally intense double kidnapping culminating in an indisputably unpredictable cliffhanger.

Understandably, this season has given a lot of screen-time to Beckett and Castle’s relationship. After spending four years teasing viewers with the possibility of their favourite crime-solving duo becoming a romantic couple, it seemed only appropriate for the show to ditch its standard formula of each case paralleling a crisis with Castle’s parenting in favour of one that saw almost every crime used to frame a speed-bump in the pair’s budding romance. In this episode, though, Alexis Castle is front and centre once more: she’s one of the two kidnapped girls.

“this is one of the most notable episodes of the season … a microcosm of the programme as a whole”

This development, which is revealed reasonably early in the episode, facilitates some of the more heart-wrenching moments seen this season. Castle’s close relationship with his daughter has been reinforced for years now, and in case you forgot about that, this episode even opens with an admittedly conspicuous conversation as to how much he misses her now she’s at college. Her kidnapping, though, doesn’t render him useless; although we see him in an emotionally fragile state, comforted by Beckett in a noticeable role reversal, he also becomes more determined, and showcases a dark side largely unseen until now. Meanwhile, Molly C. Quinn continues to confidently deliver Alexis as a vulnerable but positive and intelligent girl who tackles her situation in the way only Castle’s daughter would. Unfortunately, her cell-mate (played by Karen David) is vapid by comparison.

From here, the episode builds to its well-executed cliffhanger, then leaves the programme’s fanbase in the dark as to how exactly this very personal investigation will pan out. Even without the suspense factor, this is one of the most notable episodes of the season; there’s some rare insight into Castle’s personal life and philosophy, and Nathan Fillion seizes this opportunity to demonstrate his impressive ability to channel emotion both through his facial expression and his delivery of dialogue. Fillion is a talented actor, and this episode is perhaps the best showcase of that yet. There are only few hints towards the content of next week’s conclusion so far, but hints towards ties to Egypt’s previous regime suggest it could be explosive.

We won’t speculate on the conclusion here, as fans will no doubt be looking for as few spoilers as possible, but this episode ultimately serves as a reminder of why we love Castle so much. Its sharp turn from light-hearted cop procedural to adrenaline-fuelled drama makes this lone episode a microcosm of the programme as a whole, especially with both Castle’s relationship to Beckett and to his daughter addressed at once. Castle is an engaging, realistic drama with the ability to wreck its audience and then restore it from tears to joy in a matter of minutes – this is excellently proven here, and we hope the rest of the season can maintain this momentum.