It's Monday, a new week, so let's get a sense of what's coming up with some of the most important and interesting stories over the next seven days.

1) A trial to follow

What's happening?

On Tuesday, Malaysia's former prime minister, Najib Razak, goes on trial over corruption involving the state's 1MDB fund. He faces charges including criminal breach of trust, which he denies.

Why does it matter?

The disappearance of billions of dollars from Malaysia's state fund was one of the biggest financial scandals in history, the full implications of which are still being understood.

According to US and Malaysian prosecutors, the money, which was meant to help the people of Malaysia, instead lined the pockets of a few powerful individuals.

This is the first time for anyone to face trial over the scandal - and it's no less a figure than the man who was still governing Malaysia last May.

2) Nigeria decides

Image copyright Reuters Image caption Muhammadu Buhari attends a campaign rally

What's happening?

On Saturday, Nigerians will vote in the country's first presidential election since 2015.

Why does it matter?

Whoever wins will govern over Africa's most populous country.

There are more than 60 candidates running, but two who are realistically in with a chance of winning, both of whom are men in their 70s.

On one side is the current president, Muhammadu Buhari, who has often been absent due to illness and under whom unemployment has doubled. He can claim improved security in the north-east and his incorruptibility as plus points.

On the other side is Atiku Abubakar, a prominent businessman and philanthropist who has tried for the presidency three times before - and failed each time.

3) What will Cohen say?

What's happening?

Donald Trump's jail-bound former lawyer testifies before the US Senate on Tuesday.

Why does it matter?

This will be the first time Michael Cohen has given a detailed run-through of his relationship with the US president, in his own words.

On 6 March, Cohen will start a 36-month sentence given after he admitted campaign finance violations, tax evasion and lying to Congress.

Relations between the president and his former loyal lawyer have soured significantly, and Cohen condemned what he called his former boss' "dirty deeds" in December. He's now co-operating with investigators.

He'll now give evidence before the Senate Intelligence Committee, and the top Democrat on the panel says there are key questions he needs to answer, notably on any possible contact between the Trump campaign and Russia.

Before you get the popcorn ready, though: you should know the hearing will be in private.