Third floor) is a 1966 Indian musical mystery film directed by Vijay Anand and produced by Nasir Hussain.

The film begins on a dark night with a young girl, Rupa (Sabina), driving her car at a very high speed around the hills of Mussoorie and stopping at The Park Hotel.

Her death is declared to be suicide by everyone among the curious onlookers, including Rocky (Shammi Kapoor), a drummer, and Ruby (Helen), a dancer at The Park Hotel.

Sunita reveals to her friend, Meena (Laxmi Chhaya), that Rupa had written a letter to her on the night of her death, confessing that she was deeply in love with Rocky, and implying that they had sexual relations, and that she desperately needs to marry him.

On her way to Dehradun, Sunita meets Anil Kumar, a charming but mischievous young man, who continuously flirts with her throughout the journey.

While Sunita initially rebuffs his advances, she eventually falls in love with Anil after realising his kind and gentle nature during an unexpected overnight trip, and even confides in him about her sister's tragic death and her hatred for Rocky.

His deceit is nearly exposed by the arrival of the real owner of the mansion, Kunwarsahab Mahender Singh (Premnath), but he too surprisingly plays along and covers for Anil, and the two soon become good friends.

Anil requests Kunwarsahab to reveal the truth about him to Sunita and her father, explaining that Rupa had deeply fallen in love with him during her stay at The Park Hotel.

She aggressively pursued him despite his disinterest in her and her engagement with Ramesh, who became extremely furious on seeing her with Anil and threatened to kill Rupa in front of him.

As Kunwarsahab keeps up the pretense instead and agrees on the alliance, Anil, with no other option, writes a letter to Sunita, revealing that he is none other than her enemy, Rocky, but that he never seduced her sister and had absolutely no idea that she would kill herself over him.

As he unsuccessfully attempts to pursue and convince Sunita, Anil is approached by an investigating police officer, Inspector Das (Iftekhar), who reveals to him that Rupa had not jumped off the third floor of The Park Hotel out of desperation, but was cold-bloodedly thrown off to her death in reality.

Inspector Das shows Anil an expensive button discovered in Rupa's hand as evidence, which he believes she tore off the killer's overcoat during the time of her fall.

He is surprised to witness her drive into the mansion of Kunwarsahab, who is shocked at seeing Anil there and insists that he must stay with him in the night for not being safe anywhere.

While Kunwarsahab leaves to search for him, Anil threatens Sabina at knifepoint and forces her to confess the truth about Rupa and Ruby's murders.

She escaped to The Park Hotel with Kunwarsahab in pursuit and banged on the door of Anil's room, pleading him to let her in.

Asha had starred in two more hits for Hussain Jab Pyar Kisise Hota Hai (1961) and Phir Wohi Dil Laya Hoon (1963).

It seems Shammi Kapoor told the director to leave the shot as-is, and that was his way of showing that the light in his life, his wife, had been taken away.