Zeinab Donati, Zeinab Donati has been studying books about various Islamic subjects for more than 19 years. She is deeply interested in history and politics as well as social issues in particular those pertaining... Answer updated 2 months ago

Assalamu aleykum,

Thanks for your question.

There are many interesting and well-written books about Imam Mahdi (aj).

I recommend the following ones:

Al-Imam al-Mahdi, The Just Leader of Humanity

https://www.al-islam.org/al-imam-al-mahdi-just-leader-humanity-ayatullah...

An Inquiry Concerning Al-Mahdi

https://www.al-islam.org/an-inquiry-concerning-al-mahdi-sayyid-muhammad-...

The Promised Savior: An inquiry into the imamate of Imam Mahdi (as) from the viewpoint of Muslim thinkers

https://www.al-islam.org/promised-savior-inquiry-imamate-mahdi-viewpoint...

The Occultation of the Twelfth Imam (A Historical Background)
https://www.al-islam.org/occultation-twelfth-imam-historical-background-...

That is just one small portion of texts concerning Imam Mahdi (aj) that can be found at Al-Islam.org, there is a whole section dedicated to him (aj):

https://www.al-islam.org/library/imam-al-mahdi

Hope this is helpful inshaAllah.