While the story of Julian Assange, WikiLeaks, and the momentous leak of documents revealing the horror of the US military’s Iraq and Afghanistan wars has been retold in documentary and fictional movie form, the other principal player in the saga, whistleblower Chelsea Manning, has remained almost a peripheral figure. Looking at her life in closeup, as this intimate documentary does, hammers home what a complex, utterly abnormal existence she has led and what a high price she continues to pay: she is currently in prison again for refusing to testify against Assange. We do at least get a sense of Manning as a person – though at this stage, she comes across as a person still trying to get a sense of herself.

The story begins on a high in 2017, as Manning’s 35-year prison sentence is commuted by President Obama. Her coming out of jail coincides with her coming out as a transgender woman, and early scenes show her reacquainting herself with freedoms she never expected to experience again, such as being outside in nature or applying makeup and growing her hair.

But the more we revisit Manning’s past, the more we come to appreciate what she’s been through: early life presenting as a queer male in Oklahoma; heavy-drinking parents; military service in Iraq; solitary confinement; seven years in an all-male prison; multiple suicide attempts; all while transitioning. It doesn’t get much easier in the present either. After a spell in the public eye – including magazine interviews, rallies and Twitter campaigning – Manning embarks on an ill-advised run for the US senate, which is derailed by an equally misjudged attempt to infiltrate the so-called “alt right”.

There’s a lot of story to tell, but it is told in frustratingly vague strokes, particularly Manning’s role in the Iraq/Afghanistan leaks. There’s little examination of the ethical or political aspects of Manning’s actions, or her views on secrecy and transparency. Nor is there much interrogation of her relationships with either Assange or Adrian Lamo, the hacker-confidante who shopped her to the FBI. (Alex Gibney’s 2013 documentary We Steal Secrets covered that episode with more journalistic rigour.)

The emphasis is more on the personal and the emotional. Manning denies her transgender identity had any connection with her motivation to leak the Iraq/Afghanistan documents to Wikileaks (which passed it on to media outlets including the Guardian). “I couldn’t let those images stay inside the system or inside my head,” she says, simply.

This is very much a sympathetic fly-on-the-wall with Team Chelsea, but, considering the high drama of Manning’s life, the resultant film is muted and disjointed, and given to impressionistic images – such as landscapes out of car windows – when really the time could have been spent telling us more. Her story doubtless has chapters to come, but, at this stage, you’re left feeling worried for her future and her mental health.

•This article was amended on 24 May 2019 after the word “transgenderism” was introduced during the editing process.